How did the expansion of slavery into Mexican territories effect the mexican- American war

The expansion of slavery into Mexican territories was a major factor in the Mexican-American War. The war was fought over the disputed border between the United States and Mexico, and the issue of slavery was a major factor in the dispute. The United States wanted to expand slavery into the Mexican territories, while Mexico wanted to keep slavery out of their territories. This disagreement was a major factor in the war, and ultimately led to the United States gaining control of the disputed territories.