Black Americans in the U.S. Congress before 1950

I just read an article mentioning that there were black Americans elected as members of the U.S. Congress long before the Civil Rights movement.

Between 1850-1899: Total of 22 black American served as members of the U.S. Congress. Among them even two U.S. Senators. 

However, between 1900 and 1949: There were only 5, no U.S. Senator.

Source: https://history.house.gov/