Explain how the purchase of the Louisiana Territory and western expansion contributed to increased sectionalism in the United States.

The main way in which the purchase of the Louisiana Territory and western expansion contributed to increased sectionalism in the United States is that each new potential state that was to be entered into the Union had to determine whether it was going to be "slave" or "free"--meaning that it further divided the North and South over the issue of slavery, and eventually led to the Civil War.