Treaty of Guadalupe Hidalgo: This treaty ended the Mexican-American War in 1848, with Mexico recognizing U.S. sovereignty over Texas - with Rio Grande as its southernmost border.
Zachary Taylor: A U.S. military leader who defended disputed territory near the Rio Grande during the onset of the Mexican-American War; later became President.
Border Dispute: A disagreement over where one country's land ends and another's begins; often leads to conflict or war, like it did between Mexico and America over Texas.