The Treaty of Guadalupe Hidalgo was signed on February 2, 1848, between the United States and Mexico, marking the end of the Mexican-American War. The treaty was signed in the city of Guadalupe Hidalgo, which is now a neighborhood in Mexico City.
The war between the United States and Mexico began in April 1846, when a detachment of American troops under the command of General Zachary Taylor clashed with Mexican troops along the Rio Grande. The United States claimed that the Rio Grande was the border between the two countries, while Mexico argued that the border was the Nueces River, further to the west. The dispute quickly escalated into a full-scale war, with the United States ultimately victorious.
Under the terms of the treaty, Mexico ceded a large portion of its territory to the United States, including present-day California, Nevada, Utah, Arizona, New Mexico, Texas, and parts of Colorado, Wyoming, Kansas, and Oklahoma.
The treaty had a significant impact on both the United States and Mexico. For the United States, it marked the beginning of a period of westward expansion and territorial growth, while for Mexico, it marked the loss of nearly half of its territory and the beginning of a long period of instability and political turmoil.
References:
https://www.britannica.com/event/Treaty-of-Guadalupe-Hidalgo
https://www.history.com/this-day-in-history/zachary-taylor-fights-the-battle-of-palo-alto