Though governed by separate countries, the cities of El Paso, Texas, and Juárez, Mexico, merge into an apparently seamless metropolis in this satellite image. Acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on October 15, 2008, this false-color image shows a cityscape straddling the Rio Grande, the river that divides the United States an Mexico.
In this image, paved streets and buildings appear in varying shades of blue-gray, and red indicates vegetation. On either side of the border, the brightest shades of red appear within city limits—plants sustained by human effort. Outside the city borders, the natural landscape appears arid. Even the nearby mountain ranges appear in shades of brown and beige with only the faintest blush of red. On the Texas side of the border, a few deep red circles indicate center-pivot irrigation fields, perhaps fallow this time of year.
According to estimates from the El Paso city government, the estimated metropolitan population in 2006 was about 2.3 million: about 775,085 in the city of El Paso and the rest of county surrounding it, and just over 1.5 million in Juárez. By 2020, population was predicted to grow by more than 20 percent in El Paso and by more than 62 percent in Juárez. Time reports that the aquifer underlying the two cities is predicted to go dry in 25 years.
El Paso’s smaller population does’t necessarily mean that it uses less water. In Juárez, thousands of people were living in makeshift suburbs without running water, according to Time. Meanwhile, El Paso was paying people to remove water-guzzling lawns and trees and replace them with native desert landscaping. The dramatic difference between the two cities in how much water is available or how people in each city use it is clear in the image. From the downtown areas of each city to their surrounding suburbs, El Paso is redder than Juárez, a sign that much more water is going to maintain lawns and other landscaping in the desert climate.
NASA image created by Jesse Allen, using data provided courtesy of NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Michon Scott and Rebecca Lindsey.