The Mexican American war ended after the capture of

How did the Mexican American War end?

Treaty of Guadalupe Hidalgo Ends the Mexican-American War

Santa Anna resigned, and the United States waited for a new government capable of negotiations to form. Finally, on Feb. 2, 1848, the Treaty of Guadalupe Hidalgo was signed, establishing the Rio Grande and not the Nueces River as the U.S.-Mexican border.

Explanation:

i confess that there are several parts of this constitution which i do not at present approve, but i am not sure i shall never approve them: for having lived long, i have experienced many instances of being obliged by better information or fuller consideration, to change opinions even on important subjects, which i once thought right, but found to be otherwise. it is therefore that the older i grow, the more apt i am to doubt my own judgment, and to pay more respect to the judgment of others.