Union County, New Mexico

Union County
Location within the U.S. state of New Mexico
New Mexico's location within the U.S.
Coordinates: 36°29′N 103°28′W / 36.48°N 103.47°W / 36.48; -103.47
Country United States
State New Mexico
FoundedJanuary 1, 1894
SeatClayton
Largest townClayton
Area
  Total
3,831 sq mi (9,920 km2)
  Land3,824 sq mi (9,900 km2)
  Water7.1 sq mi (18 km2)  0.2%
Population
 (2020)
  Total
4,079
  Density1.1/sq mi (0.4/km2)
Time zoneUTC−7 (Mountain)
  Summer (DST)UTC−6 (MDT)
Congressional district3rd
Websiteunionnm.us

Union County (Spanish: Condado de la Unión) is the easternmost county in the U.S. state of New Mexico. As of the 2020 census, the population was 4,079, making it the fourth-least populous county in New Mexico. Its county seat is Clayton. The county was formed in 1894. Union County borders Colorado to the north, and Oklahoma and Texas to the east.