What national disaster most directly accounted for the population decrease in the middle states shown on the map above a. stock market crash c. World War 1 b. dust bowl d. Prohibition?

The national disaster that most directly accounted for the population decrease in the middle states is the Dust Bowl. During the 1930s, severe drought and poor agricultural practices led to massive dust storms, devastating crops and livelihoods, which prompted many people to migrate, particularly to the West. This environmental catastrophe significantly impacted the population in affected areas.