<P> The U.S. Senate approved the treaty, rejecting amendments from both Jefferson Davis to also annex most of northeastern Mexico and Daniel Webster not to take even Alta California and Santa Fe de Nuevo Mexico . The United States also paid $15,000,000 ($482 million in 2016 dollars) for the land, and agreed to assume $3.25 million in debts to US citizens . While technically the territory was purchased by the United States, the $15 million payment was simply credited against Mexico's debt to the U.S. at that time . </P> <P> The Mexican Cession as ordinarily understood (i.e. excluding lands claimed by Texas) amounted to 525,000 square miles (1,400,000 km), or 14.9% of the total area of the current United States . If the disputed western Texas claims are also included, that amounts to a total of 750,000 square miles (1,900,000 km). If all of Texas had been seized, since Mexico had not previously acknowledged the loss of any part of Texas, the total area ceded under this treaty comes to 915,000 square miles (2,400,000 km). </P> <P> Considering the seizures, including all of Texas, Mexico lost 54% of its pre-1836 territory in the Treaty of Guadalupe Hidalgo . For only fifteen years from 1821 (when Mexican independence was secured) and the Texan Revolt in 1836, the Mexican Cession (excluding Texas) formed approximately 42% of the country of Mexico; prior to that, it had been a part of the Spanish colony of New Spain for some three centuries . Beginning in the early seventeenth century, a chain of Roman Catholic missions and settlements extended into the New Mexico region, mostly following the course of the Rio Grande from the El Paso area to Santa Fe . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2010) (Learn how and when to remove this template message) </Td> </Tr> </Table>

Who sold part of mexico to the united states