What role did nationalism play in America's western expansion?

Nationalism was justification for the U.S. to expand further driving all the Natives into small reserves.

Explanation:

Nationalism and Manifestation were the driving forces that led the Americans to move westward. They assumed that because God has given them the blessing to expand, they should.

he believed that congress would be better not dealing with "lobbyists", or people who seek to influence (a politician or public official) on an issue, since historically, they had problems with these kinds of people. he thought lobbying produces benefits, but should be carefully monitored.