The Spanish name of the town derives from the O'odham name, Ṣaʼalk, which means "mountain pass".

[2] Boundaries are with Pima County and Santa Cruz County in the U.S. state of Arizona to the north; Nogales to the east; Tubutama to the south; Altar to the west; and Magdalena de Kino to the southeast.

The only settlements of over 100 population were Sáric (892) 31°06′11″N 111°22′40″W / 31.10306°N 111.37778°W / 31.10306; -111.37778, El Sásabe (1,295) 31°28′19″N 111°32′39″W / 31.47194°N 111.54417°W / 31.47194; -111.54417, and Cierro Prieto (353) 31°01′13″N 111°23′43″W / 31.02028°N 111.39528°W / 31.02028; -111.39528, as enumerated in the 2010 census.

The Altar River has its source north of the municipality in the Arizona mountains and flows south.

The desert lands are poor and agriculture can only be practiced in the Altar River valley where wheat, corn, alfalfa, sorghum, and rye grass are grown.