Old/New by Dror Poleg

Satellite data feature

How Cities Grow (or Don’t)

By Dror Poleg

Twenty cities photographed from orbit in 1990 and today. Same patch of ground, same scale, both times.

Recent frames 2024-09-01 to 2026-04-08 · settlement grids 1990 and 2025 · imagery NASA · measures EC JRC

Shenzhen

built up more than out

Shenzhen from orbit in 19901990
Shenzhen from orbit in 20262026-01-13
Built-up area
90 → 317 km²
 
3.5×
People in frame
3.4M → 14.9M
 
4.4×
People per km²
1,350 → 5,954
Per square mile
3,497 → 15,424

A fishing and farming district beside Hong Kong in the older frame, designated a special economic zone in 1980. People arrived faster than ground was added, so it is denser now as well as larger.

San Francisco

barely changed

San Francisco from orbit in 19901990
San Francisco from orbit in 20262026-04-05
Built-up area
156 → 175 km²
 
1.1×
People in frame
2.0M → 2.3M
 
1.1×
People per km²
815 → 927
Per square mile
2,113 → 2,401

Twenty square kilometres of new ground and 279,000 more people in thirty-five years. Water on three sides accounts for part of that. The rest is what was permitted.

Same thirty-five years, same fifty kilometres of ground. Shenzhen added 228 square kilometres of city and 11.5 million people; San Francisco added 20 and 279,000. Neither city is simply richer or younger than the other — they made different decisions about whether to build. Across twenty cities those decisions fall into four patterns, and a fifth that is really the absence of one.

Chengdu

absorbed its hinterland

Chengdu from orbit in 19901990
Chengdu from orbit in 20242024-10-27
Built-up area
65 → 301 km²
 
4.6×
People in frame
5.4M → 6.8M
 
1.2×
People per km²
2,175 → 2,703
Per square mile
5,634 → 7,002

Covers four and a half times more ground but holds only a fifth more people. The Sichuan basin is among the most densely farmed land on earth, so Chengdu expanded across villages rather than onto empty fields. No city here added more ground relative to its size, and few added fewer people.

Chongqing

grew in step

Chongqing from orbit in 19901990
Chongqing from orbit in 20252025-10-11
Built-up area
56 → 209 km²
 
3.7×
People in frame
3.3M → 10.0M
 
3.0×
People per km²
1,338 → 3,985
Per square mile
3,467 → 10,324

Built into river gorges and hillsides, terrain that makes every new district expensive. Ground and population grew at close to the same rate, which is what it looks like when a city adds residents and the buildings to house them at the same time.

Ho Chi Minh City

grew in step

Ho Chi Minh City from orbit in 19901990
Ho Chi Minh City from orbit in 20252025-12-21
Built-up area
122 → 385 km²
 
3.1×
People in frame
4.5M → 14.5M
 
3.2×
People per km²
1,811 → 5,787
Per square mile
4,693 → 14,992

The fourth most construction on this list. The Mekong delta is flat, wet and heavily farmed, and the city has spread across it at almost exactly the rate people arrived.

Chennai

absorbed its hinterland

Chennai from orbit in 19901990
Chennai from orbit in 20262026-02-08
Built-up area
84 → 222 km²
 
2.7×
People in frame
6.7M → 11.1M
 
1.6×
People per km²
2,690 → 4,421
Per square mile
6,969 → 11,454

Coastal Tamil Nadu was already thickly settled, so much of the new ground went over existing villages rather than empty land. The same pattern as Chengdu, less extreme.

Shanghai

built up more than out

Shanghai from orbit in 19901990
Shanghai from orbit in 20252025-11-28
Built-up area
216 → 545 km²
 
2.5×
People in frame
7.9M → 26.5M
 
3.3×
People per km²
3,174 → 10,581
Per square mile
8,222 → 27,413

Pudong, across the river from the old city, was farmland and warehouses in the older frame. Population grew faster than footprint, so the average resident lives more densely than in 1990.

Dubai

built on empty land

Dubai from orbit in 19901990
Dubai from orbit in 20252025-10-11
Built-up area
90 → 209 km²
 
2.3×
People in frame
777k → 4.4M
 
5.7×
People per km²
311 → 1,777
Per square mile
806 → 4,604

The largest population multiple here, nearly six-fold, on 2.3 times the ground. It built outward into desert with nothing in the way, and upward fast enough that people accumulated quicker than area.

Bangkok

grew in step

Bangkok from orbit in 19901990
Bangkok from orbit in 20262026-04-05
Built-up area
252 → 559 km²
 
2.2×
People in frame
6.8M → 17.3M
 
2.5×
People per km²
2,713 → 6,927
Per square mile
7,028 → 17,945

Spread along the Chao Phraya and its canal network at roughly the pace people arrived.

Beijing

grew in step

Beijing from orbit in 19901990
Beijing from orbit in 20252025-11-04
Built-up area
273 → 562 km²
 
2.1×
People in frame
7.6M → 17.7M
 
2.3×
People per km²
3,047 → 7,099
Per square mile
7,895 → 18,391

Ring roads added outward across the flat plain, with ground and population closely matched.

Cairo

grew in step

Cairo from orbit in 19901990
Cairo from orbit in 20242024-09-09
Built-up area
191 → 391 km²
 
2.0×
People in frame
11.9M → 24.5M
 
2.1×
People per km²
4,741 → 9,812
Per square mile
12,282 → 25,420

Egypt's habitable land is a thin ribbon along the Nile. Cairo doubled its footprint by climbing into the desert on both sides of the valley, which is why the new city reads as pale against the dark farmland.

Riyadh

built on empty land

Riyadh from orbit in 19901990
Riyadh from orbit in 20252025-09-01
Built-up area
221 → 421 km²
 
1.9×
People in frame
2.6M → 8.9M
 
3.4×
People per km²
1,036 → 3,562
Per square mile
2,683 → 9,228

Built into open desert with no farmland or villages to absorb. Population grew nearly twice as fast as area, so the newer districts are denser than the old core.

Tel Aviv

built on empty land

Tel Aviv from orbit in 19901990
Tel Aviv from orbit in 20252025-10-11
Built-up area
88 → 153 km²
 
1.7×
People in frame
1.6M → 4.3M
 
2.6×
People per km²
644 → 1,706
Per square mile
1,668 → 4,421

The smallest footprint of any city here. It grew mostly by filling in, with people arriving faster than ground was added.

Delhi

built on empty land

Delhi from orbit in 19901990
Delhi from orbit in 20242024-11-04
Built-up area
313 → 494 km²
 
1.6×
People in frame
11.8M → 30.0M
 
2.5×
People per km²
4,720 → 11,985
Per square mile
12,228 → 31,049

Added more than 18 million people inside the frame on only 1.6 times the ground. The result is the second densest place measured here, after Cairo.

Houston

built up more than out

Houston from orbit in 19901990
Houston from orbit in 20242024-12-06
Built-up area
276 → 430 km²
 
1.6×
People in frame
2.0M → 4.1M
 
2.0×
People per km²
808 → 1,648
Per square mile
2,094 → 4,269

Sprawl with very little in the way: flat land in every direction and no zoning of the conventional kind. It added half again as much ground and twice as many people, so even Houston is denser than it was.

Sao Paulo

grew in step

Sao Paulo from orbit in 19901990
Sao Paulo from orbit in 20252025-02-24
Built-up area
470 → 589 km²
 
1.3×
People in frame
14.7M → 18.0M
 
1.2×
People per km²
5,867 → 7,195
Per square mile
15,200 → 18,639

Already vast in the older frame and slower since. Only Tokyo and New York had larger footprints in 1990.

Paris

barely changed

Paris from orbit in 19861986
Paris from orbit in 20242024-09-01
Built-up area
361 → 427 km²
 
1.2×
People in frame
8.7M → 10.0M
 
1.1×
People per km²
3,488 → 3,994
Per square mile
9,036 → 10,347

Held its shape for four decades: a fifth more ground, a tenth more people. Among the flattest cities here on both measures.

Tokyo

barely changed

Tokyo from orbit in 19901990
Tokyo from orbit in 20252025-04-21
Built-up area
589 → 678 km²
 
1.1×
People in frame
17.5M → 20.2M
 
1.2×
People per km²
6,987 → 8,091
Per square mile
18,102 → 20,960

Builds constantly and expands not at all. Its footprint was already the largest here in 1990 and has grown a tenth since, while Japan's population peaked in 2008. Tokyo's construction replaces buildings rather than adding to the edges, a distinction satellites cannot see but building permits can.

London

built up more than out

London from orbit in 19901990
London from orbit in 20242024-10-11
Built-up area
375 → 423 km²
 
1.1×
People in frame
7.6M → 10.8M
 
1.4×
People per km²
3,020 → 4,319
Per square mile
7,825 → 11,190

A tenth more ground and 40 per cent more people, so the average Londoner lives more densely than in 1990. The green belt is visible from orbit as the line where building stops.

New York

barely changed

New York from orbit in 19901990
New York from orbit in 20262026-04-08
Built-up area
402 → 439 km²
 
1.1×
People in frame
10.1M → 11.7M
 
1.2×
People per km²
4,032 → 4,686
Per square mile
10,446 → 12,141

Already among the largest footprints here in 1990, behind only Tokyo and Sao Paulo, and barely moved since. What growth there was went upward and into the existing fabric rather than outward.

Twenty cities, two measures

Sorted by built-up area · both figures describe the square shown

How much more land each city has built on, and how many more people live there. The distance between the two columns separates cities that built for arrivals from cities that built over people already in place.

City1990 km²2025 km² Built-upPeople Per km²Pattern
Chengdu653014.6×1.2×2,703absorbed its hinterland
Chongqing562093.7×3.0×3,985grew in step
Shenzhen903173.5×4.4×5,954built up more than out
Ho Chi Minh City1223853.1×3.2×5,787grew in step
Chennai842222.7×1.6×4,421absorbed its hinterland
Shanghai2165452.5×3.3×10,581built up more than out
Dubai902092.3×5.7×1,777built on empty land
Bangkok2525592.2×2.5×6,927grew in step
Beijing2735622.1×2.3×7,099grew in step
Cairo1913912.0×2.1×9,812grew in step
Riyadh2214211.9×3.4×3,562built on empty land
Tel Aviv881531.7×2.6×1,706built on empty land
Delhi3134941.6×2.5×11,985built on empty land
Houston2764301.6×2.0×1,648built up more than out
Sao Paulo4705891.3×1.2×7,195grew in step
Paris3614271.2×1.1×3,994barely changed
Tokyo5896781.1×1.2×8,091barely changed
San Francisco1561751.1×1.1×927barely changed
London3754231.1×1.4×4,319built up more than out
New York4024391.1×1.2×4,686barely changed

Sources & Methodology

How these pictures and these numbers were made

Each city is a fixed 50 km square centred on its downtown, identical in both years. The recent frame is chosen by sweeping candidate dates across a two-year window, scoring every returned frame for cloud and swath gap from pixel statistics, and keeping the clearest. The early frame is the earliest year the WELD annual archive covers cleanly, 1990 where available. Ground covered and population are summed from the GHSL grids over the same bounding box, never derived from the photographs.

Every frame is the same 50 km square — 2,500 km², or 965 square miles — so people per square kilometre is population divided by a constant. It is the one figure here that needs no judgement about what counts as built-up: two inputs, and one of them is a number we chose rather than measured.

Imagery: NASA Worldview Snapshots (GIBS): Landsat WELD annual true colour for the early frame, HLS S30/L30 true colour for the recent one — courtesy NASA, free to reuse with attribution. Measures: EC JRC Global Human Settlement Layer R2023A, GHS-POP and GHS-BUILT-S, 30 arc-second grids, 1990 and 2025 epochs.

All research · Deep Dives · Proprietary Indicators · The Economics Canon · Research Radar · What changed? · Data & Methodology

This data is provided for informational purposes only and may incorporate third-party sources. It may be revised, delayed, incomplete, or contain errors. No warranty is made as to its accuracy, completeness, or fitness for any purpose. It does not constitute financial, investment, legal, or other professional advice. Verify important information with the original sources. This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.

Data & methodology