El Paso, Texas

Back when Texas was still Tejas, El Paso, the second oldest settlement in the United States, was the main crossing on the Rio Grande. It still plays that role today, its 600,000 residents joining with another 1.7 million across the river in Ciudad Juarez, Mexico, to form the largest binational (and bilingual) megalopolis in North America. At first sight it's not an especially pretty place – massive railyards fill up much of downtown, the belching smelters of copper mills line the riverfront, and the northern reaches are taken up by the giant Fort Bliss military base. Its dramatic setting, however, where the Franklin Mountains meet the Chihuahuan Desert, gives it a certain bold pioneer edge, bearing more relation to old rather than new Mexico, with little of the pastel softness of the Southwest US.