The Mexican Cession gave the United States a great deal of land in what is now the southwestern part of the United States. The United States got land in the present-day states of California, Nevada, Wyoming, Utah, Colorado, New Mexico, and Arizona as a result of winning the Mexican-American War. The United States paid Mexico 15 million dollars for this land. However, acquiring this land renewed tensions between the free states and the slave states.
Tensions increased because both sides saw this land as an opportunity to gain more states that would either be free or have slaves. California quickly applied for statehood, mainly due to the large increase in population in California because so many people went there to look for gold. California had to be a free state since its constitution banned slavery. With the Compromise of 1850, California was admitted to the Union as a free state. However, the Fugitive Slave Act was passed. It required northerners to help capture slaves that had escaped to the North. This led to increased tensions between the North and the South.
Both sides eyed the rest of the Mexican Cession as an opportunity to get more new states on their side. While popular sovereignty would be used to determine if the new states would or would not have slavery, both sides would ultimately push hard to either ban or allow slavery in the new states that would eventually join the Union.
As a result, tensions increased between the North and the South.