Question

What act set the tone for the westward expansion of the United States of America by establishing that new states would be formed and admitted to the United States, instead of allowing existing states to expand their territory?

Answer 1

Manifest Destiny although not a US policy did allow laws like the homestead act to be passed.  The Northwest Ordinance and the act of 1802 provided the prerequisites for admission as a new state.  I believe the reason for new States and not allowing current states to expand was because the southern states wanted to expand slavery into the new territories and the northern states did not want that to happen.  

Answer 2

Answer:  B) the Northwest Ordinance

Explanation: The Northwest Ordinance is the reason that the US has fifty states of varying size instead of 20 states with vast land. This act established the procedure by which new territories could become part of the United States.