The U.S. Congress has seen tremendous contributions from Black Americans throughout history. Some notable milestones include:

1. Hiram Rhodes Revels: In 1870, Hiram Rhodes Revels, a Republican from Mississippi, became the first Black senator in the United States Congress. He served a one-year term.

2. Shirley Chisholm: In 1968, Shirley Chisholm became the first Black woman elected to Congress. She represented New York's 12th congressional district and went on to run for president in 1972, becoming the first Black major-party candidate for the presidency.

3. John Lewis: A prominent civil rights activist, John Lewis was elected to the U.S. House of Representatives in 1986, representing Georgia's 5th congressional district. Lewis was a key figure in the Civil Rights Movement and continued to be a champion for civil rights and social justice throughout his tenure in Congress.

4. Barbara Jordan: Barbara Jordan was the first Black woman to deliver a keynote address at the Democratic National Convention in 1976. She served as a member of the U.S. House of Representatives from 1973 to 1979, representing Texas's 18th congressional district.

These are just a few examples of the many Black Americans who have made significant contributions to the U.S. Congress and have played key roles in shaping the nation's legislative history.