In the late 1800s, many more settlers moved to the west after the completion of
the transcontinental railroad.
the indian appropriation act.
the battle at wounded knee.
the reservation system.

the transcontinental railroad.

Explanation:

The transcontinental railroad is a complex set of railroads that cross the United States from coast to coast, and this opened the opportunity for more people to migrate west, as the main ports of arrival for immigrants were in the eastern coast, this helped the west to be populated and reachable. When they started populations and cities grew around the main stations of the rail road, this also developed urbanization and gentrification in places in main continental land where the railroads crossed.

the correct answer is d: "party organizers, volunteers, voters, and elected officials."

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