To see which of them left negative impressions on history, check out the list of the worst U.S. presidents ever below. In 2021, the 142 presidential historians and professional observers of the presidency that were surveyed named James Buchanan as the worst president of the 44 they reviewed. One of the most forgotten presidents in history, his pro-slavery politics are also blamed for setting up the country for the Civil War. You can view the full ranking of the 10 worst presidents of all time below. For a refresher on U.S. history, here are facts about all 46 American presidents.