Answer :
The Mexican-American War
Explanation :
The Mexican-American War allowed for the United States to gain and conquer the Southwest. This war also caused sectional conflict in the years leading up to the Civil War.
The southern slaves had a high rate of natural increase. Masters in the South preferred the black slaves as they served for lifetime with no right of being free.
The slave-holding gentry dominated the eighteenth century Virginia politics as requirements of voting favored the wealthy only.
