Freed slaves or the enslaved negroes/black farmers migrated to western territories because the west was new and the United States Agrarian Reform had promised them a free land which is forty (40) acres and a mule under the Homestead Act of 1862.
It made families sad, poor, hungry, weak....
Supply & Demand. More crops mean more job opportunities. More job opportunities & food mean more people. More people means more money. Economic growth.
D. Poverty
Hope this helps :)