Arivaca (O'odham: Ali Wa:pk) is an unincorporated community in Pima County, Arizona, United States. It is located 11 miles (18 km) north of the Mexican border and 35 miles (56 km) northwest of the port of entry at Nogales. The European-American history of the area dates back at least to 1695, although the community was not founded until 1878. Arivaca has the ZIP code 85601. The 85601 ZIP Code Tabulation Area had a population of 909 at the 2000 census. The Arivaca community lies on the northeast foothills of a small, low elevation mountain range, the San Luis Mountains.
The early history of Arivaca is obscure. It was probably a Pima or Tohono O'odham village, abandoned after the Pima Indian Revolt of 1751. Spanish settlers developed small mines.
In 1833 a Mexican land grant of 8,677 acres (35.11 km2) was approved, which became La Aribac ranch, a Pima word for "small springs". Charles Poston bought the ranch in 1856, and the reduction works for the Heintzelman Mine, at Cerro Colorado, were then erected at Arivaca. The Court of Private Land Claims eventually disallowed the Arivaca Land Grant. The US Post Office was established April 10, 1878, with Noah W. Bernard as the first Postmaster; still in operation at ZIP code 85601.