Question

What political issue was behind the question of the expansion of slavery after the Mexican War?

Answer 1

The expansion of slavery really WAS the political issue after the Mexican War, since each new state that was admitted into the Union had to determine if it was going to be "slave" or "free".

Answer 2

I believe the answer is: Compromise Act of 1850

Compromise Act of 1850 was a compromise between anti-slave states on the north with the pro-slave states on the south 2 years after the and of Mexican-american war. This compromise lead to the creation of several states where slavery was legal and several states where slavery was banned.