1848 Treaty of Guadalupe Hidalgo
The Mexican-American War began in 1846, due to territorial disputes over the southern border of the United States. In 1848, after two years of bloody fighting, Mexico City fell to the United States and the Mexicans were forced to sign the Treaty of Guadalupe Hidalgo. The treaty established the Rio Grande as the southern border of the United States and ceded vast tracts of land to the United States, adding a total of 525,000 square miles to the country’s territory. In exchange, the Mexican government received 15 million dollars. The Treaty helped establish the United States as the dominant power in North America, and defined national boundaries that still stand today.