Who lets new states become part of the united states?

A US Territory or as with Puerto Rico, a US Commonwealth, can apply for statehood into the United States first by a vote of the people in the territory. The US Congress accepts the finalized application. read more

Becoming Part of the United States. The first Mexicans to become part of the United States never crossed any border. Instead, the border crossed them. read more

The Library of Congress > Teachers > Classroom Materials > Presentations and Activities > Immigration Becoming Part of the United States The first Mexicans to become part of the United States never crossed any border. read more