Why would the South be so interested in the land to the west of the borders of the U. S., in what was then part of Mexico?

What time?

Explanation:

If it is like mid 1800s, the South want the land of the west to support slavery. If the South get these western land to accept slavery, it outnumber the states that oppose slavery (North).

was a long, primarily nonviolent series of events to bring full civil rights and equality under the law to all americans. the era has had a lasting impact on united states society, in its tactics, the increased social and legal acceptance of civil rights, and in its exposure of the prevalence and cost of racism. in the south violence and fraud in southern elections from 1868 to 1876, which had reduced black voter turnout and enabled southern white democrats to regain power in state legislatures across the south