New Mexico is roughly bisected by the Rio Grande and has an approximate mean altitude of 5,700 ft (1,737 m). The topography of the state is marked by broken mesas, wide deserts, heavily forested mountain wildernesses, and high, bare peaks. The mountain ranges, part of the Rocky Mts., rising to their greatest height (more than 13,000 ft/3,962 m) in the Sangre de Cristo Mts., are in broken groups, running north to south through central New Mexico and flanking the Rio Grande. In the southwest is the Gila Wilderness.
Broad, semiarid plains, particularly prominent in S New Mexico, are covered with cactus, yucca, creosote bush, sagebrush, and desert grasses. Water is rare in these regions, and the scanty rainfall is subject to rapid evaporation. The two notable rivers besides the Rio Grande—the Pecos and the San Juan—are used for some irrigation; the Carlsbad and Fort Sumner reclamation projects are on the Pecos, and the Tucumcari project is nearby. Other projects utilize the Colorado River basin; however, the Rio Grande, harnessed by the Elephant Butte Dam, remains the major irrigation source for the area of most extensive farming. The capital of New Mexico is Santa Fe, and the largest city is Albuquerque.