Final answer:
During the Mexican Cession, the U.S. paid $15 million to Mexico and assumed $3.25 million in Mexican debts to U.S. citizens according to the Treaty of Guadalupe Hidalgo. An additional $10 million was paid in 1854 for the Gadsden Purchase to finalize the U.S.-Mexico border and facilitate the construction of a southern transcontinental railroad.
Step-by-step explanation:
The United States paid a significant amount during the Mexican Cession following the Treaty of Guadalupe Hidalgo. This historical event occurred in February 1848 at the end of the Mexican-American War, leading to a substantial increase in U.S. territory. The treaty resulted in Mexico ceding approximately 525,000 square miles of land, which included what are now the states of California, Nevada, Utah, Arizona, and parts of Colorado, Wyoming, and New Mexico.
In compensation for the loss of this expansive landmass, the United States agreed to pay Mexico $15 million and also assumed approximately $3.25 million in debts that Mexico owed to U.S. citizens. These financial agreements were made alongside other promises, such as future U.S. citizenship for Mexican citizens living in the ceded territories and protection against Native American raids.
Additionally, in 1854, the United States paid an extra $10 million for a smaller parcel of land in the Gadsden Purchase, securing land advantageous for constructing a southern transcontinental railroad and finalizing the U.S.-Mexico border. This continued the momentum of American expansion known as Manifest Destiny.