Cities Have Doubled in Size Globally in the Last 20 Years, Study Says

New research from China finds an incredible rate of urban expansion in North America and China.

1 minute read

November 9, 2020, 6:00 AM PST

By James Brasuell @CasualBrasuell


Freeway Construction

Tim Roberts Photography / Shutterstock

Stephen Chen reports the findings of a new study from researchers in China ad published in Science Bulletin earlier this month. The key finding of the research: "The collective size of cities more than doubled over the past two decades in an unequal pace of expansion across the globe…"

"Measurements based on satellite images suggest the total size of urban areas increased from nearly 240,000 sq km (92,700 square miles) in the year 2000 to almost 520,000 sq km (200,000 square miles) in 2020," explain Chen.

The continent with the fastest rate of expansion: North America, with 3,921 square kilometers of developer land added every year over that time period. Chinese cities, infamous for a quick rate of urbanization and expansion, "trailed closely behind with a 73,300 sq km increase in total."

The research team behind the study created a new tool to define boundaries of cities, acknowledging the inaccuracies of previously extant automated processing tools, according to the article. The researchers also credited the quick rate of urban expansion in North America and China to people seeking more space to live in the relatively undeveloped expanses of the country and an intensive use of automobiles.

The news about the expansion of urban areas follows closely on the heels of news that the United Nations has updated its definition of urban, as compared to rural.

Wednesday, November 4, 2020 in South China Morning Post

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Cover CM Credits, Earn Certificates, Push Your Career Forward

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

July 16, 2025 - Diana Ionescu

Green vintage Chicago streetcar from the 1940s parked at the Illinois Railroad Museum in 1988.

Chicago’s Ghost Rails

Just beneath the surface of the modern city lie the remnants of its expansive early 20th-century streetcar system.

July 13, 2025 - WTTV

Blue and silver Amtrak train with vibrant green and yellow foliage in background.

Amtrak Cutting Jobs, Funding to High-Speed Rail

The agency plans to cut 10 percent of its workforce and has confirmed it will not fund new high-speed rail projects.

July 14, 2025 - Smart Cities Dive

Worker in yellow safety vest and hard hat looks up at servers in data center.

Ohio Forces Data Centers to Prepay for Power

Utilities are calling on states to hold data center operators responsible for new energy demands to prevent leaving consumers on the hook for their bills.

July 18 - Inside Climate News

Former MARTA CEO Collie Greenwood standing in front of MARTA HQ with blurred MARTA sign visible in background.

MARTA CEO Steps Down Amid Citizenship Concerns

MARTA’s board announced Thursday that its chief, who is from Canada, is resigning due to questions about his immigration status.

July 18 - WABE

Rendering of proposed protected bikeway in Santa Clara, California.

Silicon Valley ‘Bike Superhighway’ Awarded $14M State Grant

A Caltrans grant brings the 10-mile Central Bikeway project connecting Santa Clara and East San Jose closer to fruition.

July 17 - San José Spotlight