Blue hatched area shows approximate region culturally known as Northern New Mexico
The traditional southern boundary of the area is an escarpment called La Bajada southwest of Santa Fe. The other boundaries are poorly defined. The map in Cobos (1983) is a guide: from La Bajada the boundary runs northwest about 50 miles (80 km) west of U.S. Routes 285 and 84, and northeast about 20 miles (30 km) east of Interstate 25, to the Colorado border. The area might also be described roughly as comprising Rio Arriba, Los Alamos, Taos, and Colfax Counties; northeastern Sandoval County, northern Santa Fe County; and western San Miguel and Mora Counties, possibly with parts of adjoining counties. To the west is the Four Corners region; to the east are the high plains of Eastern New Mexico.