Which war resulted in territorial gains for the united states that caused sectional conflict in the years leading up to the civil war? revolutionary war war of 1812 mexican war spanish-american war

The Mexican war

Explanation:

The Mexican war was the war that resulted in territorial gains for the united states. and this war led to sectional conflicts in the United states of America over whether slavery should be permitted in the newly acquired territory.the Mexican war lasted from 1846 to 1848

The Mexican war was the war between America and Mexico and the major cause of the war was the Annexation of Texas in 1845 by United states of America. America won the war and Gained Texas permanently as its territory. the civil war followed the Mexican war several years later.  

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