An astronaut aboard the International Space Station (ISS) took this photograph of the eastern parts of Tijuana, located in the Mexican state of Baja California about 20 kilometers (12 miles) inland from the Pacific Ocean. Tijuana is one of the fastest growing metropolitan areas in Mexico.

Note the sharp demarcation between Mexico and the United States. Tijuana shares this international border with its sister city San Diego, California, and it is the busiest land-border crossing in the world, with more than 300,000 crossings every day. The population of entire Tijuana-San Diego metropolitan region was estimated in 2012 to be about 4.9 million people.

The image shows Tijuana’s rugged terrain, which includes canyons and steep-sided hills such as Cerro Colorado (Red Hill). The photo is detailed enough to show individual roads and highways. The largest visible in the view is the double highway that follows the Rio Tijuana along both its banks. The Mexicali-Tijuana highway (top center) curves around a mountain near the border. Switchbacks of a steep dirt road wind up the side of a canyon, leading to the border fence road and to the peak of Otay Mountain.

Astronaut photograph ISS051-E-13155 was acquired on April 14, 2017, with a Nikon D4 digital camera using an 1150 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 51 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by Justin Wilkinson, Texas State University, JETS Contract at NASA-JSC.