The Municipality of Altar, is one of the 72 municipalities of the Mexican state of Sonora, located in the northwest of the state bordering the United States border and located in the Sonoran Desert. Its municipal head and more populated locality is the homonymous town of Altar, other important localities are White Plain, September 16, among others. It was named as a municipality on October 31,1825 under the name of Villa Figueroa Municipality. According to the intercensal survey of 2015 conducted by the INEGI, has a total of 9,578 inhabitants, the municipality has an area of 3,944 km². Its Gross Domestic Product per capita is USD 8,539 and its human development index is 0.8186.
Like most of the municipalities of Sonora, the name was given by its head, the town of Altar.