The main reasons for restrictions among certain professions in the late 1800s were racially-motivated, in that African Americans were not allowed to hold many positions that were deemed to be only for whites (especially in the South), such as military positions, positions in medicine, law, etc.
One of the outgrowths of the civil rights movement of the 1960s was an emphasis on multiculturalism, the belief that the American society should maintain and protect its diversity by laws.