Some of the worst presidents in United States history, according to U.S. News & World Report, include Andrew Johnson, James Buchanan and Warren G. Harding. All three presidents presided over policy blunders, forcing their successors to try to fix their mistakes.
Andrew Johnson succeeded Abraham Lincoln following Lincoln's assassination in 1865, putting a racist Southern politician at the head of the country's reconstruction efforts. Johnson refused to force Southern states to give black Americans and former slaves full rights. He granted a slew of pardons to former Confederate rebels and vetoed two pro-black laws, the 1866 Civil Rights Act and the Freedmen's Bureau bill. He was impeached by the Senate but was acquitted by one vote.
James Buchanan from Pennsylvania served as president at the start of the Civil War from 1857 to 1861. He opposed slavery but refused to make it any part of his federal agenda, believing it to be a states' rights issue. He felt he had no right to stop any state from seceding from the Union. He also supported the entry of Kansas as a slave state, however, the state would eventually enter the union as a free state.
Warren G. Harding presided in the White House from 1921 to 1923 before dying of a heart attack while in office. He surrounded himself with corrupt officials to whom he left much of the decision making, while he played poker and philandered with women. He also reversed many of the financial policy measures of Woodrow Wilson's administration.