"The first African American Members, Senator Hiram Revels of Mississippi and Representative Joseph Rainey of South Carolina, both took the oath of office in 1870. These first two Members were among the 22 African American Members (2 in the Senate, 20 in the House) that began their service in the period of time after the Civil War but prior to the start of the 20th Century. After these first 22, the presence of African Americans in the Membership of Congress was not continuous and there were subsequent periods in both chambers with no African American Members. Most recently, the 115th Congress began with the highest number of African American Members ever at the start of a Congress: 51 (46 Representatives, 2 Delegates, and 3 Senators)."
CRS Report for Congress, RL30378