Gustavo A. Madero (gōstäˈvō ä mädāˈrō) [key], city (1990 pop. 1,268,068), Federal District, S central Mexico. Formerly called Guadalupe Hidalgo, it was renamed in 1931. It is the site of the Our Lady of Guadalupe shrine and is a major Roman Catholic pilgrimage center. The treaty of Guadalupe Hidalgo (1848), which ended the Mexican War, was signed there.