Which group did not generally participate in the prosperity of the 1920s?

Black people suffered economically, especially in the southern states, where segregation was in effect. The ancestors of the black people in the south had been slaves.

Many immigrants had not been educated and were willing to work in any kind of job for very low wages. Because of this, they endured more and more prejudice.

The traditional industries failed to respond to the new mass-production methods of the 1920s, unlike the Ford company that was making a good profit and could pay impressive wages. 

a. competition with other nations.

after the french-indian war.