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A TALE OF FIVE CITIES AND HOW THEY GREW

BY CLARE TRAINOR, JASON TREAT, AND KELSEY NOWAKOWSKI

Rail, roads, and real estate play a role in the physical shape of cities. So does geography. To track how metropolitan regions have developed, Shlomo Angel and his colleagues at New York University used historical maps and satellite imagery to create the Atlas of Urban Expansion. The atlas defines city parameters to include the entire built area beyond a city’s jurisdictional boundaries and into surrounding municipalities.

INNOVATIONS THAT SHAPED CITIES

RESISTING ATTACK

Walls long protected cities from invaders. Cannons became a threat—until residents developed thick, sloped walls able to withstand blasts. Once nation-states made the walls unnecessary, cities could spread out.

FACILITATING TRADE

Port cities flourished as global centres of industry. To move cargo inland, rail lines extended out from the cities into the country in all directions. This led to tentacle-shaped development patterns.

MOVING PEOPLE

When the elevator was introduced in the 1850s, cities grew denser and taller. Cities were able to stretch farther into the suburbs when cars and buses filled in the transportation gaps left by rail lines.

LOS ANGELES, UNITED STATES

Real estate developer Henry Huntington bought up land on the outskirts of Los Angeles in the late 1890s. Then he established the Pacific Electric Railway to link the scattered suburbs. The interurban rail system, which operated from 1901 to 1961, propelled the city’s expansion and for a time was the world’s largest electric-powered system. Eventually it was dismantled and replaced by bus lines and cars, making sprawl the norm.

Pacific Electric Railway in 1920

Urban extent by year

2014

2000

1990

1980

1950

1920

PACIFIC

OCEAN

1890

LONDON, UNITED KINGDOM

With the opening of the London Underground in 1863, the city spread outward. The Cheap Trains Act of 1883 allowed working-class people to move from grim tenement blocks to railway suburbs. London added the bulk of its population between 1800 and 1900, growing from 1.1 million people to 6.5 million.

SHANGHAI, CHINA

What had been a relatively compact industrial city of 12 million people in 1982 has now doubled. The city rapidly spread in the 1980s when the government began opening the country to foreign investment. Shanghai’s physical footprint has swelled so quickly that population density has declined since the 1990s.

MANILA, PHILIPPINES

Situated between the sea and a lake, the city expanded on a north-south axis. Since 1950, nearly 50 percent of the Philippines’ urban population growth has been in the Manila area. That intensified from 1980 to 2000, when almost all the urban growth took place in the city’s suburbs.

LAGOS, NIGERIA

After Nigeria gained independence from the British Empire in 1960, oil production soared, bringing people and money to the capital. Now coastal wetlands are being drained to meet development demands from foreign investors and rural Nigerians migrating to the city.

CLARE TRAINOR, JASON TREAT, KELSEY NOWAKOWSKI, AND LAUREN LEADMON
SOURCES: SHLOMO ANGEL AND ALEJANDRO BLEI, ATLAS OF URBAN EXPANSION, NEW YORK UNIVERSITY; PACIFIC ELECTRIC RAILWAY; LOS ANGELES RAILROAD HERITAGE FOUNDATION; COPYRIGHT OPENSTREETMAP CONTRIBUTORS, AVAILABLE UNDER OPEN DATABASE LICENSE: OPENSTREETMAP.ORG/COPYRIGHT