Why do you think the federal government, rather than state government, set policies for westward expansion?

Signed into law by Abraham Lincoln during the Civil War, the Homestead Act encouraged westward migration and settlement by providing 160-acre tracts of land west of the Mississippi at little cost, in return for a promise to improve the land.

Explanation: please mark as brainliest

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.