The Mexican-American War was a conflict between America and Mexico. From 1846 through 1848, the countries waged this war because of the fight for land expansion and independence of Texas from unofficial Mexican rule. In the end, the Mexican-American War contributed to the formation of the USA’s geographical borders because the treaty of Guadalupe Hidalgo gave the US more than 500,000 square miles of land, perpetuated slavery in the south, and encouraged the idea of Manifest Destiny until the end of the 18th century. To start, Manifest Destiny was the ideology used by white Americans to justify the expansion of their land across all of North America. An event in history most commonly associated with the ideology of Manifest Destiny is the Mexican-American