How did Tokyo grow from swampland to 37 million? | Maps in Motion #01
Short answer
- In 1590, Edo was inlets and wetlands with a small town around its castle and port; by the 18th century it held about 1 million people.
- Large parts of the city burned three times — 1657, the 1923 Great Kanto Earthquake, the 1945 air raids — and each time it grew back bigger.
- Odaiba, Yume no Shima, and the expanded part of Haneda Airport were all once sea.
Video
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Explained
How did a small castle town on the marshes grow into a metropolitan area of 37 million people? This video fast-forwards 430 years of Tokyo on a map, from 1590, when Ieyasu Tokugawa moved into Edo, to the city of today.
Data behind the maps
The maps in the video are built from the figures below. Anything marked "estimate" was spread across the map from overall totals, or drawn by hand from historical accounts (the video description calls these "approximations").
Population
"City core" means central Tokyo, the area of today's 23 special wards. "Tokyo Metropolis" is the whole of Tokyo Prefecture. "Greater Tokyo" is the wider metropolitan area that takes in Tokyo and the surrounding prefectures.
| Year | Area | Figure |
|---|---|---|
| 18th century | Edo | Over 1 million, one of the largest cities in the world at the time |
| Summer 1945 (end of the war) | City core | Down to roughly 40% of its wartime level, after air raids and evacuations |
| 1962 | Tokyo Metropolis | Passes 10 million |
| 1965 | City core | 8.89 million |
| Today | City core | Still setting new records |
| Today | Greater Tokyo | About 37 million, more than the entire population of Australia |
How the population dots were made
The more people live in a place, the denser the dots. Where people have just started living, the dots flash vermilion before settling into black ink. The figures behind the dots differ by period.
| Period | What the dots are based on | Type |
|---|---|---|
| Edo, before 1868 | Population spread over about 30 hand-drawn town districts | Estimate |
| 1872–1965 | Totals for each prefecture and for the city core (census figures from 1920 on), spread out according to how close each place is to open railway lines and town centers | Estimate |
| 1970–1990 | Worked back from the 1995 census 1 km grid (population per 1 km square), with totals matched to census figures for each prefecture; the shape of the built-up area comes from satellite data on buildings (GHSL) | Estimate |
| 1995–2020 | Census 1 km grid population used as is, then redistributed onto built-up areas in squares of 31–500 m | Census figures |
Land and sea (reclamation)
| Year | Place | What happens on the map |
|---|---|---|
| 1590 | Edo's shoreline | The sea reaches deep inland, with marshes around the castle and the inlet (shoreline is an estimate; some details may be off by a few hundred meters) |
| Around 1592, 1603 and 1620 | Hibiya Inlet | Filled in to become land in three stages (shape is an estimate) |
| Edo period (1603–1868) | Hatchobori, Tsukiji, Fukagawa, Sunamura and other areas | Reclamation creeps out to sea from the 1590 shoreline (shapes are estimates) |
| Around 1868 | Shoreline at the end of the Edo period | The coast as Edo became Tokyo (estimate) |
| Meiji era (1868–1912) to today | Reclaimed land in Tokyo Bay (Tsukishima, Toyosu, Odaiba and more) | Each plot appears in the order it became land. In the "eating the sea" scene, land that used to be water turns wheat-colored (eras read from the colors of the Tokyo Bay Environmental Information Center's map by era, lined up with today's coastline) |
| 1931 | Haneda Airfield | A small airfield of 53 hectares with a single 300 m runway (shape is an estimate) |
| 1957–1967 | Yumenoshima ("Dream Island") | Grows as it is filled with Tokyo's garbage |
| Today | Haneda Airport | 1,522 hectares (about 30 times its 1931 size) and 4 runways; the newest stand out over the water |
| Today | Tokyo Bay | More than 70 artificial islands; reclamation has cost the bay much of its tidal flats |
| Today | Low-lying land | Some of it sits below sea level (areas under 0 m, from GSI elevation data, are tinted) |
Railways and towns
| Year | Event | What happens on the map |
|---|---|---|
| 1868 | Edo is renamed Tokyo ("eastern capital") | — |
| 1872 | Japan's first railway opens between Shinbashi and Yokohama | Vermilion rail lines begin to appear |
| By 1920 | Railways radiate outward from the center | Population dots build up along the lines |
| 1923 | In Den-en-chofu, homes go on sale on hills that used to be farmland, and commuting into the center by train starts to spread | The Den-en-chofu area appears (shape is an estimate) |
| 1950s–1965 | Houses rise from the ashes, railways stretch outward, and hills are carved into new neighborhoods | The burned areas fill in and the dots spread west into the hills |
| 1971 | Families begin moving into Tama New Town | The green Tama Hills turn into housing (shape of the development area is an estimate) |
Railways are drawn as 139 sections of 67 lines, in order of opening year, with the tip of each line glowing as it grows. Opening years come from the Japanese Wikipedia article on each line.
Three great fires
| Date | Event | Area burned | Deaths |
|---|---|---|---|
| 1657 | Great Fire of Meireki | About 60% of Edo | Tens of thousands (reported) |
| September 1, 1923, just before noon | Great Kanto Earthquake (and the fires that followed) | More than 40% of Tokyo | Over 100,000 across the Kanto region |
| Early hours of March 10, 1945 | Great Tokyo Air Raid (about 300 American bombers) | Much of eastern Tokyo, in a single night | About 100,000 (reported) |
The burned areas on the map are estimates, drawn by hand from historical accounts.
Maps and satellite data used
| Used for | Data and date | Provider |
|---|---|---|
| Today's coastline, rivers, moats, ponds, railways, stations and Haneda's runways | OpenStreetMap data for the Kanto region (Geofabrik extract), retrieved October 5, 2026 | © OpenStreetMap contributors |
| Land beyond the Kanto region (wide shots out to all of Japan) | Natural Earth 10m (world map data at 1:10 million scale) | Natural Earth |
| Hill shading, lowland tint, land below sea level, rough extent of former marshes | GSI elevation tiles (dem_png) | Geospatial Information Authority of Japan (GSI) |
| Eras of reclaimed land, from the Meiji era to today | "Land reclamation by era in Tokyo Bay" (a map color-coded by era) | Tokyo Bay Environmental Information Center |
| Population dots, 1995–2020 | Japanese census grid statistics (1 km squares, every five years) | e-Stat, Statistics Bureau of Japan |
| Fine texture of the dots; urban extent 1970–1990 | GHSL GHS-BUILT-S R2023A (built-up surface seen from satellites; 1975, 1990, 2005, 2020) | European Commission Joint Research Centre |
| Night views at the opening, the pull-back and the ending | NASA Black Marble (2016 annual composite of night lights) | NASA |
No old maps or historical aerial photos were used. The 1590 and late-Edo shorelines, Edo's castle, moats and town districts, the burned areas, Den-en-chofu and Tama New Town, and the 1931 Haneda Airfield were drawn by hand as estimates, using today's terrain, the locations of place names and historical accounts. Place-name data from old Edo district maps (kiriezu) was left out, because the orientation and scale of each sheet were unknown and the maps could not be lined up accurately.
What this episode shows
- Edo, which Ieyasu Tokugawa moved into in 1590, was not born but built: its inlet was filled in, moats were dug, and the marshland itself was remade.
- Large parts of Edo and Tokyo burned three times, in the Great Fire of Meireki (1657), the Great Kanto Earthquake (1923) and the Great Tokyo Air Raid (1945), and each time the city came back bigger, spreading west along the railways and into the Tama Hills.
- Tokyo also grew into the sea: Tsukishima, Toyosu, Odaiba, Yumenoshima and the newer parts of Haneda Airport were all once water, and Tokyo Bay lost much of its tidal flats along the way.
Shorts
Sources
Where the facts and numbers in the video and on this page come from.
- e-Stat statistical GIS, Statistics Bureau of Japan (census grid statistics (1 km, 1995–2020), the basis of the population dots, in Japanese. Retrieved October 5–6, 2026)e-stat.go.jp/gis/statmap-search
- e-Stat, Statistics Bureau of Japan (long-term census population series by prefecture (1920–2005), used for prefecture totals from 1920 to 1990. Retrieved October 5, 2026)e-stat.go.jp
- Japanese Wikipedia, "Special wards of Tokyo" (census population table for the city core (1920–1995), in Japanese. Date viewed not recorded)ja.wikipedia.org/wiki/東京都区部
- Tokyo Bay Environmental Information Center ("Land reclamation by era in Tokyo Bay," used for the eras of reclaimed land, in Japanese. Retrieved October 5, 2026)tbeic.go.jp
- GSI tile list, Geospatial Information Authority of Japan (elevation tiles (dem_png) for terrain shading, lowlands and land below sea level, in Japanese. Retrieved October 5–6, 2026)maps.gsi.go.jp/development/ichiran.html
- OpenStreetMap (© OpenStreetMap contributors (ODbL). Today's coastline, rivers, moats, railways and stations (Geofabrik Kanto extract). Retrieved October 5, 2026)openstreetmap.org/copyright
- Natural Earth (10m land data (public domain). Retrieved October 5, 2026)naturalearthdata.com
- GHSL, European Commission Joint Research Centre (GHS-BUILT-S R2023A (1975, 1990, 2005, 2020). © European Union, 1995-2024. Source: European Commission Joint Research Centre (CC BY 4.0). Retrieved October 5, 2026)ghsl.jrc.ec.europa.eu
- NASA Earth Observatory, "Night Lights" (NASA Black Marble (2016 annual composite). Credit: NASA. Retrieved October 5, 2026)earthobservatory.nasa.gov/features/NightLights
- Japanese Wikipedia, "Zero-meter zone" (land below sea level, in Japanese. Date viewed not recorded)ja.wikipedia.org/wiki/ゼロメートル地帯
- IPCC Sixth Assessment Report (sea-level rise. Date viewed not recorded)ipcc.ch/assessment-report/ar6
- Japanese Wikipedia (historical facts (articles on Edo, Hibiya Inlet, the Great Fire of Meireki, Tokyo, the Tokaido Main Line, the Port of Tokyo, Den-en-chofu, the Great Kanto Earthquake, the Great Tokyo Air Raid, Tokyo Metropolis, Tama New Town, Yumenoshima, Haneda Airport, Odaiba, Tokyo Bay, the Greater Tokyo Area and others) and opening years from each railway line's article (67 lines, 139 sections), in Japanese. Date viewed not recorded)ja.wikipedia.org
