"Jim Crow" was the nickname given to the laws introduced into the South during the 19th and 20th centuries to enforce racial segregation. "Jim Crow" became synonymous with all the racial abuses associated with the southern states. The name stuck during the civil rights era.
Jim Crow was a minstrel show character from the 1830's. He was portrayed as an elderly, crippled and clumsy African American slave and his portrayal showed all the negative stereotypes of African Americans - the black man with his white master with Jim Crow being thankful for his lot in life. Jim Crow was an uneducated man who had his white master to thank for being looked after etc.
Such stereotyping caused huge resentment to African Americans during the civil rights era.