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 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. While northern New Mexico, also known as the or upper river area, did receive a lot of Hispanic settlement, much Hispanic colonial settlement also occurred in southern areas, known as the or lower river. The distinction between and dates back to colonial times, and continues to be a cultural and linguistic division in New Mexican Hispano society. ==Governmental==