because northern political interests were against the addition of a new slave state
Explanation:
the United States declined to integrate it into the union, primarily because the northern political forces were resistant to the creation of a modern slave state. The Mexican Government even supported border attacks and threatened that any effort at invasion would lead to war.Initially, the United States declined to integrate it into the union, primarily because the northern political forces were resistant to the creation of a modern slave state. The Mexican Government even supported border attacks and threatened that any effort at invasion would lead to war.
