Answer:
To encourage railroad construction across the Great Plains, the federal government gave land grants to many railroad companies. The railroads then sold the land to settlers, real estate companies, and other businesses to raise money to build the railroad.
Explanation:
<span>This is of course somewhat of a subjective question, but in general most would agree that in general expansion was not justifiable since the Mexicans and Natives were doing nothing to provoke the US. One could argue it was justifiable since Americans needed more land. </span>
