Respuesta :

The Mexican-American War lasted from 1846 to 1848, and most of it was all about Texas. Once Texas declared that it was independent from Mexico, they elected Sam Houston as their first President. This all changed in 1845 when Texas was accepted as the 28th state of the United States.
America wanted Mexico in order to spread slavery and the idea that it was the nations duty to imperialize others. Polk claimed American blood was shed on Mexican ground so it was the right of America to imperialize it.