How did the war between Mexico lead between the north and the south?

Answer 1

Because it added vast new territories to the USA, and there was disgreement over which of these would be slave-states and which would be free soil.

Answer 2

The vast new territories which became part of the United States following the Mexican War threatened to upset the delicate balance in the Congress. As the territories applied for statehood, the question of whether the state would be slave or free would have to be debated and new compromises made. Eventually, the two sides polarized and legislative gridlock made the South look for extralegal means to preserve their Property Rights and States Rights, which were only euphemisms for slavery.

Answer 3

Mexico was not a major player in the US Civil War. African slavery was the major cause of the war.