Texas is the 28th state to join the Union and become a part of the United States.
After Texas joins the Union, Mexico and the United States argue about whether the Rio Grande or the Nueces River constitutes the border.
Both sides sent troops to the border to end the argument. Mexico fired first, prompting America to declare war.
Against all odds, the Mexican army prevails at the Battle of Buena Vista in February 1847. They constituted a significant turning point in the conflict despite being vastly outnumbered.
General Winfield Scott of the United States reached Mexico City in 1847 and took control of the city by hoisting the American flag over the Montezuma Hall.
With the signing of the Treaty of Guadalupe Hidalgo in 1848, the Mexican-American War was finally put to a conclusion. For $15 million, the United States acquired 525,000 square miles of land, designating the Rio By Aryan Gupta Grande as its southern border.