Treaty that ended the Mexican War, confirming the US victory. Mexico gave up California, Arizona, New Mexico, Nevade, Utah, western Colorado and any claim to Texas, marking the US border as the Rio Grande, resulting in Mexico halving in size. In return the US paid Mexico $15 million. When the Senate come to ratify the treaty, the Wilmot Proviso, an amendment banning slavery in any territory gained from Mexico, was rejected, a mark of the increasing tension over the issue of slavery.