The Treaty of Guadalupe Hidalgo. Background. The Treaty of Guadalupe Hidalgo (gwah-dah-loop-ay ee-dahl-go), which brought an official end to the Mexican-American War (1846-1848) was signed on February 2, 1848, at Guadalupe Hidalgo, a city north of the capital where the Mexican government had fled with the advance of U.S. forces.