Nogales (nōgäˈlās) [key], city (1990 pop. 19,489), Santa Cruz co., S Ariz. on the Mexican border with its adjacent city, Nogales (1990 pop. 105,873), Sonora, NW Mexico. There are copper, silver, and lead mines. Skirmishes occurred in Nogales against Pancho Villa in 1916. Industrial development, primarily between 1980 and 2000, in the Mexican area of Nogales resulted in a growth of maquiladoras, Mexican manufacturing plants employing low-cost labor to produce goods for the U.S. market.