Question

What is the main factor in American expansionism west?

Answer 1

Instead, he finds that population growth and technological innovation worked in concert as the main driving factors of Western Expansion.

Answer 2

The most important forces are population growth and the decrease in transportation costs," Vandenbroucke said. "Population growth is mostly responsible for the investment in productive land - without it less than half of the land accumulated in 1900 would have been accumulated."