Andrew Johnson became president after Lincoln's death. Johnson's plan of reconstruction included having the defeated Southern states pledge their loyalty to the Union and abolish slavery. By the fall of 1805, all Confederate states, except Texas, rejoined the Union. Many southern state governments passed laws called "black codes," which limited the rights of freed African Americans. In 1868, the Fourteenth Amendment was added to the Constitution. It made freed blacks citizens of the United States and guaranteed them the same legal rights as whites.

In 1865, Congress created the Freedmen's Bureau to provide help for both blacks and whites in need. Unable to pay freedmen to work the fields, many white Southern landowners began to rent their lands to blacks and poor whites in exchange for as much as one half of the crops grown on that land. Congress passed the First Reconstruction Act, which allowed African Americans to be elected to state offices and Congress. President Johnson was charged with wrongdoing and almost removed from office.

Former Confederate officers formed the Ku Klux Klan to terrorize African Americans and their white supporters. The Fifteenth Amendment was added to the Constitution in 1870. stating that states could not deny male citizens the right to vote "on account of race or color." Rutherford B. Hayes became president in 1877 and ended Reconstruction. Jim Crow laws were passed in Southern states, which made the separation of white and black people legal in schools, restaurants, trains, hotels, and parks.