How did the united states expand its borders to include 48 of todays 50 states?

What stalled germany's initial invasion into france in 1914

23. how does specialization among nations encourage interdependence? nations work together to share labor and resources to produce vital goods. nations sign treaties prohibiting taxes on imports. nations produce specific goods and then trade to obtain things they need. nations that are more developed agree to fund development in nations with limited industry.

Brainliesttt !me : ) describe the responses to terrorism in the united states.