Answer:
Gold rush and mining opportunities (silver in Nevada, Gold Rush in California)
The opportunity to work in the cattle industry; to be a “cowboy”
Faster travel to the West by railroad; availability of supplies due to the railroad
The opportunity to own land cheaply under the Homestead Act
The discovery of wheat strains adapted to grow in the climate of the Plains.
New inventions allowing them to adapt to life on the Plains, such as the windmill and barbed wire (students may need to speculate as to why homesteaders needed these)
Adventure and the lure of the “Wild West”
New Opportunities
Manifest Destiny