As Americans pushed west, the issue of slavery came to the forefront. Would the new territories of the United States be slave or free?

The territories had to decide for themselves.

Explanation:

The territories that were slave territories were west of the south east US, and northern territories were free. There were conflicts deciding whether the territories wanted to be free or not such as Bleeding Kansas, a civil conflict that added to the pre-Civil War tension of the union.

uncle sam would be tossing and turning in his grave : *)