1868-1870: Congress adopts the 14th & 15th Amendments.

1868, July 9:  Congress ratifies the 14th Amendment, establishing that African americans are citizens.  It also provides all Americans with due process and equal protection under the law.

1870, February 3:  Congress ratifies the 15th Amendment, prohibits the federal government and the states from using a citizen's race, color or previous status as a slave as a qualification for voting.  However,  it still excludes all women from voting.