The main reason was the South wanted to preserve slavery. The North wanted to abolish it. If you want some other reasons than slavery, let me know, and I will do my best to add more to this answer.
The Treaty of Guadalupe Hidalgo, which brought an official end to the Mexican-American War<span> (1846–48), was signed on February 2, 1848, at Guadalupe Hidalgo, a town near Mexico City. The U.S. paid Mexico $15 million and absorbed another $3 million in debts, and acquired New Mexico, Arizona and California.</span>
In 1849, Europeans came to in search for <span>gold
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