Methodology, Data Sources, and Update Cadence

What every piece has in common

Each visualization shows one dataset, or one pair of datasets, from a named public source. The sources, the preparation of each series, and the last period included are listed on the piece's own page. The visualization is a single self-contained file that can be opened directly or embedded on any page. No interpretation is offered; what the data shows is left to the viewer.

Format: line and sphere

The first pieces use one format. A series is drawn as a line, left to right, over the number of seconds the piece names. A second quantity is drawn as a sphere at the leading edge of the line. The animation holds briefly on the most recent period and loops. A scrubber pauses on any point.

The sphere's on-screen area is proportional to the second quantity, relative to the largest value in the series. A sphere with twice the area represents twice the value. This is the convention used by most bubble charts because people judge circles by area. Each piece also offers two alternatives in its controls: volume-proportional (radius scales with the cube root, which makes small values more visible) and logarithmic (each tenfold increase adds the same width). A three-pixel minimum keeps the smallest values visible.

Format: priced in a unit

A dollar amount is divided by the price of one unit — an hour of work, for example — and the result is drawn as a line, left to right, over the number of seconds the piece names. The unit's price is drawn as a sphere at the leading edge of the line, scaled by area as in the line-and-sphere format, with the same three scaling options in the controls. The animation holds briefly on the most recent period and loops. Where the unit has a natural shape, the sphere is replaced by that shape — a house, for example — scaled by area in the same way. The playback speed can be changed in the controls, from a quarter speed to double.

Format: nested spheres

A series is drawn as a line, left to right, over the number of seconds the piece names. Two quantities are drawn as spheres at the leading edge of the line, one inside the other, scaled by area on a single scale so that the inner sphere's share of the outer sphere's area is its share of the value. The same three scaling options are offered in the controls. The animation holds briefly on the most recent period and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: rungs

Two series are drawn as two lines, left to right, over the number of seconds the piece names. A vertical gap line joins them at a fixed interval and stays where it was drawn, so the history of the gap reads as a ladder; the one at the leading edge is drawn bright and carries the gap's value. Where the two lines cross for good, a diamond marks the point, placed between the two periods on either side of the crossing in proportion to their values. Short notes, computed from the data, mark the moments the piece is about. The animation holds on the most recent period and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: phase path

Two series are plotted against each other, one on each axis, so each period is a single point and the periods in order trace a path. A marker walks the path over the number of seconds the piece names. Older segments are drawn fainter, and line color and width follow the point's distance from the center of the whole series, on a scale stated on the piece's page. Because neither axis is time, a thin timeline below the plot carries one bar per period, colored as the path is, with a playhead at the period being drawn. The animation holds briefly on the most recent period and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: event calendar

A list of dated events is drawn as dots on a calendar plane: the year across, and the day of the year up, January at the bottom and December at the top. Every dot is the same size, so a crowded year is crowded because it holds more events. Events in an emphasized class are ringed, once or twice, and counted separately above the chart. A short tick on the year axis marks a year with no events. The years are drawn in left to right over the number of seconds the piece names; the animation holds on the latest year and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: unit grid

A total is drawn as a field of identical squares, each worth a fixed unit, filling in order as the total grows: left to right in groups of ten — fifty to a row on a wide screen, twenty on a phone held upright — so a row reads as short bars rather than single marks. The field holds the rows the latest total needs, and every square not yet filled is drawn faintly in the same grid. The year printed beside a row is the year its first square filled and the figure at its right end is the total when the row was complete, so the spacing of the years down the field is the rate of growth; a headline compares how long the first and the latest blocks of the same size took. The next square fills from the bottom to the fraction of the unit reached; squares added within the past year are drawn pale with a dark dash; a square empties in a period the total falls below it. The periods are drawn in over the number of seconds the piece names; the animation holds on the latest and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: spiral

A monthly series is drawn as one line winding out from a center, one full turn per year, the twelve months at twelve fixed angles with January at the top. The line's distance from the center is the month's value on a linear scale, and a bright ring marks the series' reference level — the average, or zero — with values below it inside the ring and values above it outside, the same distance for the same amount either way. Faint rings mark the scale at even steps, labelled once up the January spoke. The line's color marks broad spans of years, the latest twelve months are drawn heaviest, and a marker rides the latest month. The months are drawn in over the number of seconds the piece names; the animation holds on the latest month and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: rising tide

A total made of parts is drawn as a stacked area: time runs left to right, the height at any period is the total, and the total is cut into bands, one per part, in a fixed order from bottom to top, so a band's thickness is that part's amount and the top edge is the whole. Each band is lit along its top boundary rather than filled solid, and the total's edge is drawn brightest with a marker at the latest period. The value scale is not fixed: it grows with the largest total drawn so far, rounded up to a round gridline step, so the early periods are drawn at a readable height and the picture zooms out as the total climbs; the gridlines are redrawn at round numbers as the scale changes. Each band is labelled at the leading edge with its current value and share in the series' own unit; on a phone held upright, a table below the picture gives them. The periods are drawn in over the number of seconds the piece names; the animation holds on the latest period and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: pyramid

A population split in two and ranked in bands is drawn as one closed, stepped outline: the bands run up the page, and at each band the outline reaches left for one side and right for the other, as far as that group's share of the whole, so the parts of an outline always add up to 100%. Outlines drawn side by side share one fixed scale and one set of bands. Time is not an axis: each frame is one period, and the outline moves between them. Every outline is filled, with a hairline between its bands; an estimate's edge is solid and lit and a projection's is dashed, and a strip under the picture marks the period where estimates end. A ring marks the largest band of each outline, its two sides counted together, on the longer side. The totals, which the shares do not show, are written with each name. The periods run over the number of seconds the piece names; the animation holds on the last period and loops. The playback speed can be changed in the controls, from a quarter speed to double.

Format: ticking bars

A fixed-order set of members, each with a running total that moves up or down by period, is drawn as one bar each, left to right by the period the member joined; nothing ever changes places. Each period every bar ticks by that period's figure, and a member's bar appears in its first period. Above the zero line a bar is a solid lit slab; below it, a hollow outline that glows. Both sides of the line share one scale, set by whichever side needs more room — that side's running high-water mark, rounded up to the next step — so the chart opens small, grows and never shrinks, and a bar above the line and one below it are the same length for the same amount. A mark may ride just beyond each bar's tip, and a subject with no marks leaves the slot empty. The line runs on into a panel that carries the period and the highest and lowest bars. The periods run over a number of seconds the piece names; the animation holds on the last period and loops. On a phone the format has two arrangements, one for a phone held upright and one for a phone held sideways, both the same chart.

A subject whose totals only ever rise is drawn one-sided: the line drops to the foot of the plot, every bar stands on it and is solid, and nothing is drawn below the line. Everything else — the fixed order, the marks at the tips, the panel, the scrubber — is the same chart. The playback speed can be changed in the controls, from a quarter speed to double.

Format: glass sphere

A store that fills and drains is drawn as one glass sphere, and the liquid inside it is the amount held. The sphere fills by the area of its circle: the share of the circle below the surface is the share held, so half full sits at the middle and the surface moves fastest near empty and near full. The sphere is full at a named capacity or, where a store has none, at the highest amount on the record, and the label above it says which. Where the capacity itself grows over the years, as when new lakes are built, the share is of the capacity on each date. Marks at a quarter, a half and three quarters stand beside the glass, except where one would sit on a dashed line. A piece may draw a dashed line at a level that matters and change the liquid's colour while the level is below it. The readout, inside the picture, carries the date, the amount and the share. The animation runs the record over a number of seconds the piece names, holds on the last date and loops. The scrubber under the chart carries a mark for every year and labels the decades, or every fifth year on a short record. On a phone the sphere and the readout are arranged one way for a phone held upright and another for a phone held sideways; the sphere is the same. The playback speed can be changed in the controls, from a quarter speed to double.

Format: sounding

A store, or several stores side by side, is drawn as a narrow straight-walled shaft full at the most it has ever held or at a stated capacity, so the height of the liquid is exactly proportional to the amount and the empty depth above it is how far the store stands below the top. A line is dropped from the bar at the top to the surface, with a weight resting on the liquid and marks every tenth of the way. With several shafts, each has its own high, so stores in different units share one picture as shares of their own records, and a shaft is drawn empty and dashed before its record begins. Each shaft's share, name and amount stand under it, and the date runs at the top. The animation runs the record over a number of seconds the piece names, holds on the last date and loops.

Format: balance

Two amounts that belong together — what something makes and what it uses — are drawn as vessels hanging from the two ends of a beam, what it makes in gold on the left and what it uses in blue on the right. The beam tips toward the heavier side, in proportion to the gap between the two against their total, and lies level on a violet parity line when they are equal. A balance's two vessels share one scale, fixed across the years and printed beneath it; different balances can have different scales, so vessels are compared within a balance, not across balances. Each balance's headline is what it makes as a share of what it uses. The animation runs the record over a number of seconds the piece names, holds on the last date and loops.

Format: crowd balance

A balance whose two pans carry crowds of people instead of liquid: each mark stands for a fixed number of people, the same on both sides of a balance, and a last mark drawn faint stands for part of that number. Each crowd is split into women and men. The beam tips toward the larger crowd and lies level on a violet parity line when the two are equal. Each balance can have its own mark size, printed beneath it, so crowds are compared within a balance, not across balances. The headline is how many times larger the bigger crowd is. The animation runs the record over a number of seconds the piece names, holds on the last date and loops.

Format: drifting center

A map on which each member of a published list sits at its own fixed location, and one ringed dot marks their center: the average of their latitudes and of their longitudes, weighted as the piece states. When a member joins or leaves the list the center moves, leaving a line behind it; when the list stays the same, the center stays put. Members fade in when they join and out when they leave. A piece may add a reference point for comparison, drawn as a violet diamond with its own faint line. The map is the lower 48 states on an Albers equal-area projection, drawn from the Census Bureau's state outlines; while every member is in the East it shows the eastern states only. The animation runs the record over a number of seconds the piece names, holds on the last date and loops. A piece may weight the members, as the business center of gravity weights companies by revenue: then each dot's area is the member's share of the year's total, the center moves when the weights change as well as when members join or leave, the roster names the ten largest, and a member new to the list is drawn larger and brighter for its first years. A piece may keep the same members throughout, as the GDP center of gravity keeps the 50 states and DC: then only the weights move the center, the line under the date names a member that passes another in the roster's top ten, and when the whole path is short an enlarged copy of it is drawn in a box beside the map. The comparison may itself be a second weighted center of the same members, drawn as its own path year by year, as the income center of gravity draws the center of people beside the center of income. A piece may instead draw a line — the meridian that splits the members in half east and west — with the median center on it, beside the ordinary average center, as the population mid-line does.

Format: state year-map

A state year-map fills each of the 50 states and the District of Columbia with a color for the year shown, and steps through the years. Where the colors are ranks, a strip of bars beneath the map carries the national figure for each year, so the map shows who led and the bars show how the whole country did.

Format: name mosaic

A name mosaic fills a fixed block with one tile per name, sized by its count and laid largest first in rows, and glides each tile to its new place from year to year.

Format: word grid

A word grid gives each year a column and each word a row, colors each cell by how often the word appears that year compared with its own busiest year, and fills in the columns from left to right.

Format: ribbon

A ribbon draws two measures as lines across the years and fills the gap between them with the color of whichever is ahead.

Format: line

Line: one measure drawn year by year as a single glowing line over a fading fill, with its record high and low marked.

Format: bullseye

Bullseye: a center disc and rings, each ring split between two sides filling from the top, so the side that reaches the bottom holds the majority.

Format: line with two measures

Line with two measures: two measures drawn year by year as glowing lines over their own fading fills, on one scale from zero.

Format: line with dots

Line with dots: a measure averaged over several years as a glowing line, with each single year's value as a faint dot behind it.

Format: petal wheel

Petal wheel: a wheel of categories, each with petals that grow outward as the count builds up year by year, with the year's own items lit around the rim.

Format: line and stacks

Line and stacks: a yearly average drawn as a line, above that year's items drawn as stacks of small squares, one square for each unit.

Format: share bands

Share bands: the parts of a whole as stacked bands that always fill the height, the subject rising from the bottom.

Format: open share bands

Open share bands: the same stacked shares on a fixed scale, when together they fill only part of the whole.

Format: year dots

Year dots: every item of a year as a dot at its value, with bands marking the ranges the story is about.

Format: year columns

Year columns: one stacked column for each year, the subject at the bottom.

Format: count grid

Count grid: one dot for every item of a year, the ones counted lit from the bottom; on upright phones the grid turns so the years run down.

Format: real-time count

Real-time count: a clock runs for fifty-six seconds and the marks pile up at their true average rate each second; there are no years to step through, and the scrubber marks seconds.

Format: bar race

Bar race: the largest members as bars that re-sort every period, the largest on top, with members sliding in and out below the last bar.

Format: timeline lanes

Timeline lanes: horizontal lanes that share one time axis and fill from left to right, so reading down at any year shows what each lane held then.

Bitcoin market cap

In the current pieces the sphere is bitcoin's market capitalization: month-end price multiplied by the number of bitcoin mined to that date. Price comes from the Coin Metrics community dataset through spring 2026 and from published monthly closes after that. Coins mined are computed from the halving schedule, which matches reported circulating supply to within a fraction of a percent. Values before July 2010, when there was no meaningful market, are nominal placeholders of a fraction of a cent.

Series notes

10-year Treasury yield — monthly average of the constant-maturity yield. Federal Reserve Bank of St. Louis, FRED series GS10.
Federal funds rate — monthly average of the effective rate. FRED series FEDFUNDS.
Fed balance sheet — total assets, last Wednesday of each month. FRED series WALCL.
Gold — US dollars per troy ounce, month end. 2009–2024 from historical London fix and spot records; 2025 onward from published monthly closes.
US national debt — total public debt outstanding. Quarter-end values from FRED series GFDEBTN through March 1993, interpolated between quarter-ends; the last business day of each month from the US Treasury's Debt to the Penny from April 1993.
Average hourly wage — average hourly earnings of production and nonsupervisory employees, total private, seasonally adjusted. FRED series AHETPI (Bureau of Labor Statistics).
10-year Treasury yield, 1953 onward — monthly average of the constant-maturity yield from the series' start. FRED series GS10.
Gold market cap — the month's average London price per troy ounce (World Bank Commodity Price Data from 1960; the official US price of $35 per ounce before that) multiplied by an estimate of all the gold ever mined: the World Gold Council's mid-2026 above-ground stock of 222,600 tonnes, carried back and forward by annual world mine production from the USGS, spread evenly across the months of each year.
Median new home price — median sales price of new single-family houses sold in the United States, monthly, not seasonally adjusted. FRED series MSPNHSUS (Census Bureau and HUD, New Residential Sales).
Federal interest payments — federal government current expenditures on interest payments, quarterly, seasonally adjusted at an annual rate. Bureau of Economic Analysis; FRED series A091RC1Q027SBEA.
Federal defense spending — national defense consumption expenditures and gross investment, quarterly, seasonally adjusted at an annual rate. Bureau of Economic Analysis; FRED series FDEFX.
Unemployment rate — civilian unemployment rate, seasonally adjusted. FRED series UNRATE (Bureau of Labor Statistics).
Inflation — the Consumer Price Index for All Urban Consumers, all items, seasonally adjusted (FRED series CPIAUCSL, Bureau of Labor Statistics), as the percentage change from the same month a year earlier.
US hurricane landfalls — every hurricane recorded as making landfall on the continental United States since 1851, with its Saffir-Simpson category at landfall, from NOAA's Hurricane Research Division; landfall dates from the division's detailed landfall list, checked against NOAA's HURDAT2 best-track database, and, for 1971–1982, from National Hurricane Center storm reports; converted to local standard time.
Federal funds rate — monthly average of the effective federal funds rate. FRED series FEDFUNDS (Board of Governors of the Federal Reserve System).
WTI crude oil — spot price of West Texas Intermediate crude, dollars per barrel, monthly, not seasonally adjusted. FRED series WTISPLC, the St. Louis Fed's splice of FRED's OILPRICE (through July 2013) and MCOILWTICO (Energy Information Administration, from August 2013).
Global surface temperature — the monthly global mean land–ocean temperature index, as the difference in degrees Celsius from the 1951–1980 average, from NASA's Goddard Institute for Space Studies (GISTEMP v4, the GLB.Ts+dSST table). The index combines land station records with sea-surface temperatures; NASA revises recent months as late station reports arrive.
Federal receipts by source — the federal government's receipts by fiscal year in nominal dollars, from the Office of Management and Budget's Historical Tables: Table 2.1 for individual income, corporation income, social insurance and retirement, and excise receipts, and Table 2.5 for the split of "other receipts" into estate and gift taxes, customs duties and fees, and miscellaneous receipts. The tables begin the customs split in fiscal 1940; the 1976 transition quarter is excluded; the total drawn is the sum of the six sources, which the tables' rounding of components leaves one or two million dollars from the published total in some years. OMB restates the tables each February with the new budget.
Federal outlays by function — the federal government's outlays by fiscal year in nominal dollars, from the Office of Management and Budget's Historical Table 3.1, grouped from its published budget functions into six bands: national defense; Social Security; Medicare and health; income security, veterans and education; net interest; and all other functions net of undistributed offsetting receipts. The table begins in fiscal 1940; the 1976 transition quarter is excluded; the total drawn is the sum of the six bands, which the table's rounding of functions leaves one to three million dollars from the published total in some years. OMB restates the tables each year with the new budget.
Immigrants by region — persons obtaining lawful permanent resident status in the United States, by decade and by region of last residence (country of origin before 1906), from the Department of Homeland Security's 2019 Yearbook of Immigration Statistics, Table 2, grouped into six bands. The table's definitions change over time — seaport passenger arrivals before 1868, incomplete counts of land arrivals before 1908, no Canada or Mexico figures for 1886–1893 — and the series stops at the 2010s because later yearbooks give only recent years, rounded.
Population pyramids: United States, China, Japan — population on 1 July by five-year age band and sex, from the United Nations' World Population Prospects 2024: estimates for 1950–2023 and the medium-variant projection for 2024–2100. Each group is drawn as a share of its own country's total that year. The source's figures for China exclude Hong Kong, Macao and Taiwan, and those for the United States exclude its territories. The United Nations revises the whole series, estimates included, with each edition.
Population pyramids: United States, Niger, South Korea — the same United Nations series, estimates for 1950–2023 and the medium-variant projection for 2024–2100, each group drawn as a share of its own country's total that year. This chart's scale runs to twelve percent a side, because Niger's youngest groups exceed ten. Where the source publishes zero for an age group, the outline has no width there.
Population pyramids: United States, Russia, Iran — the same United Nations series, estimates for 1950–2023 and the medium-variant projection for 2024–2100, each group drawn as a share of its own country's total that year, on the ten-percent scale of the United States, China and Japan chart. The source's names are the Russian Federation and "Iran (Islamic Republic of)".
Hockey Hall of Fame birthdays — every player inducted into the Hockey Hall of Fame through the 2026 class, from the players table of Wikipedia's list of members, with each player's date of birth from their Wikipedia article and checked against Wikidata; the article's date is used where the two disagree, and the position is the list's, a goaltender where the list and Wikidata agree.
Major League no-hitters — every no-hitter officially recognised by Major League Baseball, taken as the numbered rows of Wikipedia's list of them, with the date, teams, league and catcher as that list gives them; a game counts as a perfect game where the list italicises the pitcher, checked against Wikipedia's separate list of perfect games.
Days with a violent tornado — every day on which at least one tornado rated F4 or above touched down in the United States, from the Storm Prediction Center's whole-track tornado file; the dot is the day rather than the tornado because 656 violent tornadoes fall on 415 days and the calendar draws one dot per day, and a day is ringed where one of its tornadoes was rated F5. Ratings are made by damage survey after the event and the practice has changed over the period.
Days a US bank failed — every day on which at least one FDIC-insured institution failed, from the FDIC's BankFind failures record, with open-bank assistance transactions excluded; the dot is the day rather than the bank because 3,525 failures fall on 1,672 days, and a day is ringed where one of the institutions held $1 billion or more in assets at failure, in the dollars of the day.
Net wins of every current NFL club — each club's regular-season wins minus losses, added up season by season from 1920, from Wikipedia's list of each club's seasons: APFA and NFL seasons, the AFL's 1960–69 and the AAFC's 1946–49, which the league's record counts; ties move nothing and the postseason is not counted. A bar follows the franchise under its current name; the merged wartime seasons of 1943 and 1944 are credited to Philadelphia and to the Cardinals, as the record credits them, and the 32 finals sum to +348 because the balancing losses belong to defunct clubs.
Net wins of every current NBA club — each club's regular-season wins minus losses, added up season by season from 1946–47, from Wikipedia's list of each club's seasons: the BAA's three seasons, which the NBA counts as its own, and every NBA season since. The ABA and the NBL are not counted, so the four clubs that came from the ABA begin in 1976–77. A bar follows the franchise under its current name; Charlotte's stands still for the two seasons the club did not exist, and the 30 finals sum to +274 because the balancing losses belong to defunct clubs.
Net wins of every current MLB club — each club's regular-season wins minus losses, added up season by season from 1876, from Wikipedia's list of each club's seasons: the National League, the American Association from 1882 and the American League from 1901, which the league's record counts. The National Association of 1871–75 is not counted. Ties move nothing and the season tables do not record them; the two halves of 1981 are one season. A bar follows the franchise under its current name, and the 30 finals sum to +1,525 because the balancing losses belong to defunct clubs.
Net wins of every current NHL club — each club's regular-season wins minus losses, added up season by season from 1917–18, from Wikipedia's list of each club's seasons and of the six predecessor franchises the league credits to a club playing today. An overtime or shootout loss counts as a loss; a tie, played until 2004–05, moves nothing. The NHA and the WHA are not counted, so Edmonton begins in 1979–80. Every bar stands still through the cancelled 2004–05 season, the Coyotes are listed among the clubs that no longer play, and Utah begins in 2024–25 as a new bar.
Total wins of every current NFL club — each club's regular-season wins, added up season by season from 1920, from the same Wikipedia season lists the net-wins chart draws: APFA and NFL seasons, the AFL's 1960–69 and the AAFC's 1946–49, which the league's record counts. Losses and ties both move the bar by nothing, so no bar ever falls. Chicago is the tallest bar for 102 seasons and Green Bay passes it in 2022; the 32 finals add up to 16,552 wins.
Total wins of every current NBA club — each club's regular-season wins, added up season by season from 1946–47, from the same Wikipedia season lists the net-wins chart draws: the BAA's three seasons, which the NBA counts as its own, and every NBA season since. The ABA and the NBL are not counted. Boston is the tallest bar for fifty-two of the eighty seasons; the 30 finals add up to 67,568 wins.
Total wins of every current MLB club — each club's regular-season wins, added up season by season from 1876, from the same Wikipedia season lists the net-wins chart draws; the strike-split 1981 season is counted once, and losses and ties both move the bar by nothing. The Chicago National League club is the tallest bar for seventy-nine seasons in all and San Francisco has been since 1966; the 30 finals add up to 221,408 wins.
Lake Mead storage — Lake Mead's elevation at Hoover Dam on the last day of each month since February 1935, from Reclamation's daily record, with the amount held read from Reclamation's 2009 area and capacity tables for every month, early ones included, because Reclamation's early storage figures rest on older surveys of the lake. Full is 26,120,000 acre-feet at 1,219.64 feet; the dashed line is 1,035 feet, from Reclamation's analysis of Hoover Dam's turbines.
Strategic Petroleum Reserve — the crude oil held in the US Strategic Petroleum Reserve, from the Energy Information Administration: monthly ending stocks from October 1977 to July 1982, weekly from 20 August 1982. Full is the record high, 726.6 million barrels in the week of 1 January 2010, because the reserve has at times held more than its authorized capacity of 714 million barrels.
US natural gas in storage — working gas in underground storage in the Lower 48 states, weekly from the Energy Information Administration since the week ending 1 January 2010. Full is the Lower 48's design capacity as of November 2025, 4,683 billion cubic feet; the stock has never reached it.
Texas reservoir storage — the water held in the water-supply reservoirs the Texas Water Development Board monitors, as a share of the conservation capacity of the lakes built by each date, monthly from 1950. The share is the Board's percent full; the Board revises its estimates as lakes are resurveyed.
US official gold reserves — the United States' official gold stock in tonnes, from Federal Reserve and Treasury dollar figures at the official price of the day ($35, $38, then $42.2222 an ounce): monthly 1947–1970, quarterly 1971–1975, year-end 1976–2001, weekly since December 2002. The high is 21,894 tonnes in September 1949.
Helium in federal storage — the helium the U.S. Geological Survey reports in federal storage at the Cliffside field near Amarillo, Texas, at each year's end, from its historical statistics compiled with the Bureau of Land Management; the high is 194,000 metric tons in 1980. The government sold its helium system in 2024.
Official gold reserves by country — each country's official gold reserves in tonnes, monthly from the International Monetary Fund's international liquidity statistics (gold reserves by volume, in fine troy ounces, converted at 32,150.7466 to the tonne). The figures begin in December 1950 for the United States, France and Germany, December 1977 for China and December 1993 for Russia.
US post offices — the number of post offices in each year, from the Annual Report of the Postmaster General as tabulated by the USPS Historian; the count peaked at 76,945 in 1901.
US farms — the U.S. Department of Agriculture's annual estimate of the number of farms, from 1910 (National Agricultural Statistics Service); the estimate peaked at 6,813,700 in 1935 and has steps where it was revised, visible in 1975, 1993 and 2007.
US public school districts — regular public school districts, from the National Center for Education Statistics' Digest of Education Statistics, every year or two from the 1939–40 school year, placed at the year each school year ends; the Center notes that figures before 1976–77 are partly estimated.
Oil made and used by country — oil production (crude oil, including lease condensate, plus natural gas plant liquids) and oil consumption, in thousand barrels a day, annually from the U.S. Energy Information Administration's international energy statistics. The Administration reports no natural gas plant liquids for the United Kingdom before 1984 or for China before 2000. The pieces pairing the United States with two other countries begin in 1984, the first year the Administration gives both figures for all of them.
Immigrants and emigrants by country — people born abroad living in a country (immigrants) and people born in it living abroad (emigrants), each by sex, from the UN Population Division's International Migrant Stock 2024, for 1990, 1995, 2000, 2005, 2010, 2015, 2020 and 2024. These are numbers of people living somewhere at each date, not yearly moves.
Second Layer — series DataSlapper compiles itself from lists others publish: the members a source names at each date, and something measured about them that no one publishes as a series. Each piece's Method gives the whole recipe, and the page serves every row it uses.

The final point in each series is the current period to date, except where a piece's Method says the series ends at the latest complete month.

Update cadence

Series are refreshed after period end, typically in the first week of the following month. The "Updated" date on each page is the last period included.

Credits

Federal Reserve Economic Data (FRED), Federal Reserve Bank of St. Louis. Bitcoin price and supply data: Coin Metrics community data, used with attribution. Gold: LBMA and published spot records. Federal debt: US Treasury, Fiscal Data. Gold price and stock: World Bank Commodity Price Data, World Gold Council, and the US Geological Survey. Home prices: US Census Bureau and HUD. Federal spending: US Bureau of Economic Analysis. Unemployment and consumer prices: US Bureau of Labor Statistics. Hurricanes: NOAA Hurricane Research Division and the National Hurricane Center. Federal funds rate and Treasury yields: Board of Governors of the Federal Reserve System. Oil prices: US Energy Information Administration, via FRED. Temperature: NASA Goddard Institute for Space Studies, GISTEMP v4. Federal receipts: Office of Management and Budget, Historical Tables 2.1 and 2.5. Federal outlays: Office of Management and Budget, Historical Table 3.1. Immigration: U.S. Department of Homeland Security, Office of Homeland Security Statistics, Yearbook of Immigration Statistics 2019, Table 2. Population by age and sex: United Nations, Department of Economic and Social Affairs, Population Division (2024), World Population Prospects 2024, Online Edition, made available under a Creative Commons licence, CC BY 3.0 IGO; the shares and totals drawn are calculated from it. Hockey Hall of Fame players: Wikipedia's list of members and the players' articles (CC BY-SA 4.0), checked against Wikidata (CC0). Major League no-hitters: Wikipedia's list of no-hitters and its list of perfect games (CC BY-SA 4.0). Violent tornado days: the NOAA Storm Prediction Center severe weather database, a work of the United States government. Bank failure days: the FDIC BankFind record of failures and assistance transactions, a work of the United States government. NFL net wins: Wikipedia's lists of each club's seasons and its list of all-time win–loss records (CC BY-SA 4.0); the club marks are the property of the clubs and the National Football League and identify the teams. NBA net wins: Wikipedia's lists of each club's seasons and its list of all-time NBA win–loss records (CC BY-SA 4.0); the club marks are the property of the clubs and the National Basketball Association and identify the teams. MLB net wins: Wikipedia's lists of each club's seasons and its list of all-time Major League Baseball win–loss records (CC BY-SA 4.0); the club marks are the property of the clubs and Major League Baseball and identify the teams. NHL net wins: Wikipedia's lists of each club's seasons, its list of all-time NHL standings and its 2025–26 NHL season standings (CC BY-SA 4.0); the club marks are the property of the clubs and the National Hockey League and identify the teams. NFL total wins: the same Wikipedia sources as the NFL net-wins chart (CC BY-SA 4.0); the club marks are the property of the clubs and the National Football League and identify the teams. NBA total wins: the same Wikipedia sources as the NBA net-wins chart (CC BY-SA 4.0); the club marks are the property of the clubs and the National Basketball Association and identify the teams. MLB total wins: the same Wikipedia sources as the MLB net-wins chart (CC BY-SA 4.0); the club marks are the property of the clubs and Major League Baseball and identify the teams. Lake Mead: the U.S. Bureau of Reclamation — its RISE daily elevation record for Lake Mead at Hoover Dam and its 2009 Lake Mead area and capacity tables (public domain); the 1,035-foot level is from Reclamation's Post-2026 Draft Environmental Impact Statement, Technical Appendix 15. Strategic Petroleum Reserve: the U.S. Energy Information Administration, U.S. Ending Stocks of Crude Oil in SPR, monthly and weekly (public domain); the authorized capacity is from the Department of Energy. US natural gas in storage: the U.S. Energy Information Administration, Weekly Natural Gas Storage Report and its storage-capacity estimates (public domain). Texas reservoirs: the Texas Water Development Board, Water Data for Texas, with thanks. What Washington Kept: the Federal Reserve Bank of St. Louis (FRED) for the National Bureau of Economic Research's gold stock series, the Federal Reserve's financial accounts and H.4.1 release; the Treasury Bulletin via FRASER; the Energy Information Administration; and the U.S. Geological Survey and Bureau of Land Management (public domain). Gold reserves by country: Source: International Monetary Fund, International Liquidity statistics; converted from fine troy ounces to tonnes. The Great Consolidation: the USPS Historian, from the Annual Report of the Postmaster General; the U.S. Department of Agriculture's National Agricultural Statistics Service, Quick Stats; and the National Center for Education Statistics, Digest of Education Statistics (public domain). Oil Made, Oil Used: the U.S. Energy Information Administration, International Energy Statistics (public domain). Immigrants and emigrants: United Nations Department of Economic and Social Affairs, Population Division (2024), International Migrant Stock 2024, used under CC BY 3.0 IGO. Cities: US Census Bureau (Working Paper 27, 1998; the 2000, 2010 and 2020 censuses; centers of population) and US Geological Survey, Geographic Names Information System, both public domain; state outlines: us-atlas 3.0.1 (ISC license), from the Census Bureau's cartographic boundary files. Companies: annual reports (Form 10-K) filed with the US Securities and Exchange Commission, from EDGAR and the SEC's XBRL financial data, public domain. State GDP: US Bureau of Economic Analysis, regional accounts (GDP by state), public domain; state centers of population: US Census Bureau, 2020 census, public domain. State personal income and population: US Bureau of Economic Analysis, regional accounts (personal income by state), public domain. Real GDP growth by state: US Bureau of Economic Analysis, regional accounts, public domain. County populations 1790–1870: US Census Bureau, Population of States and Counties of the United States: 1790 to 1990 (1996), public domain; median centers of population: US Census Bureau, Centers of Population Computation for the United States 1950–2020, public domain. State population estimates: US Census Bureau, midyear estimates, as published by the US Bureau of Economic Analysis in its state personal income accounts, public domain. Baby names: US Social Security Administration, national baby-name data from Social Security card applications, public domain. State of the Union texts: Richardson's Compilation of the Messages and Papers of the Presidents (Project Gutenberg), Foreign Relations of the United States, the Congressional Record and the Compilation of Presidential Documents, US government works; the American Presidency Project (UC Santa Barbara) used as a check only. Sentiment word list: VADER lexicon, C. J. Hutto and E. Gilbert (2014), MIT licence. Syllable counts: the syllable package by Titus Wormer, MIT licence. Party divisions: U.S. Senate Historical Office and the Office of the Historian, U.S. House of Representatives. Top 20 hits: Billboard's year-end Hot 100, as reproduced by Wikipedia; song details from Wikipedia, SongBPM and other song pages. GDP by state: U.S. Bureau of Economic Analysis. Wars and U.S. deaths: U.S. Department of Veterans Affairs, “America's Wars” fact sheet. Federal minimum wage: US Department of Labor, Wage and Hour Division; silver prices: US Geological Survey (Historical Statistics for Mineral and Material Commodities, Mineral Commodity Summaries, Minerals Yearbook and Mineral Industry Surveys).

Data tables

Each visualization page carries the values the chart draws, as a table below its sources, exactly as they are embedded in the chart's file.

Accuracy

These are visualizations, not a data service. Values are rounded to the period shown, and the placement of a point within a period is a drawing convention rather than a claim about timing. If you spot an error, use the contact page; corrections are noted on the affected visualization.