Farmington is a city in San Juan County in the U.S. state of New Mexico.Farmington makes up one of the four Metropolitan Statistical Areas in New Mexico.Farmington is located at the junction of the San Juan River, the Animas River, and the La Plata River, and is located on the Colorado Plateau. Farmington is the largest City, and one of only two significant towns, of San Juan County, one of the largest counties in the United States covering 5,538 square miles (14,340 Square Kilometer). The county seat and the other city in San Juan County is Aztec. Farmington serves as the commercial hub for most of northwestern New Mexico and the Four Corners region of four states. Farmington lies at or near the junction of three important highways U.S. Highway 550, U.S. Highway 64, and New Mexico Highway 371.