The town was named after General Stephen Watts Kearny, who passed through the area on November 7, 1846, while leading 100 dragoons to California.

[2] The economic base of Kearny and nearby towns is the Ray mine and Hayden Smelter, both owned and operated by ASARCO.

Kearny was built by the Kennecott Mining Company in 1958 as a planned community to accommodate the populations of nearby Ray, Sonora and Barcelona, which were about to be swallowed by Kennecott's expanding open-pit copper mine.

While many houses in the town were newly built, some mine employees had their homes moved down the road.

[3] The town sits near the Gila River in the Copper Basin area along with its sister cities, Hayden and Winkelman.

According to the United States Census Bureau, the town has a total area of 2.8 square miles (7.3 km2), all land.