Final answer:
Hiram Rhodes Revels became the first black senator in American history in 1870. He was a former minister and Mississippi state senator before his election to the U.S. Senate.
Step-by-step explanation:
The first black senator in American history, who was elected in 1870, was Hiram Rhodes Revels. He rose to prominence as a minister in the African Methodist Episcopal Church and then as a Mississippi state senator in 1869, before being elected to the U.S. Senate the following year. Senator Revels's election was a significant historical event as he took the seat that had been vacant since the Civil War, representing a major step forward in the political representation of African Americans after the abolition of slavery.