What event is credited with ending the mass migration to the northern plains?

The correct event that is credited with ending the mass migration to the northern plains is the Great Depression. The Great Depression, which began in the late 1920s and lasted through much of the 1930s, brought severe economic hardship across the United States, impacting agriculture and the livelihoods of those living in rural areas.

During this period, many farmers faced challenges such as falling crop prices, bank failures, and severe droughts, which made staying in the northern plains increasingly difficult. Consequently, this economic crisis led to a significant decrease in migration to the region as individuals and families sought more stable conditions elsewhere, often moving to urban centers in search of jobs.

While World War I, the Dust Bowl, and World War II had significant impacts on American society and migration patterns, it was the combination of economic devastation during the Great Depression and the environmental disasters, such as the Dust Bowl, that particularly curtailed the flow of people moving to the northern plains for agricultural opportunities.