The chart above was made with information from fivethirtyeight.com. It shows that Donald Trump is the most unpopular president since 1945. The figures shown are the net approval ratings (approval minus disapproval) of each president after being in office for 175 days.
Note that only two presidents have a net approval rating in negative numbers -- Gerald Ford (after giving Nixon a pardon) and Donald Trump. And Trump's rating is 10 points worse than Ford's. We have never, since World War II, had a president as unpopular as Donald Trump.
