Then and Now

Cities: as Seen Through Landsat Satellites

In honor of the 40th anniversary of the Landsat satellite system, which has been taking photos of Earth from space since 1972, NASA and the U.S. Geological Survey created an interactive website where you can see the growth of cities around the world over the past four decades.
This one above is the Pearl River Delta in China:

In 1979, China established two special economic zones around the Pearl River Delta, north of Hong Kong. This image, taken by Landsat 3 on October 19, 1979, shows that the region was rural when the zone was established. Plant-covered land, which is red in this false-color image, dominates the scene. Square grids are agriculture.
By January 10, 2003, when Landsat 7 took this image, the Pearl River Delta was a densely populated urban corridor with several large cities. The urban areas are gray in this image. The region is a major manufacturing center with an economy the size of Taiwan's. As of 2010, the Pearl River Economic Zone had a population of 36 million people.

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