By the end of his time in office, Truman was an unpopular president with a low approval rating. He was so unpopular that he did not run for reelection in 1952, instead backing Adlai Stevenson.

Part of the problem was serving in the shadow of one of the most popular and revered presidents of all time, Franklin Roosevelt. Nobody was likely to look good in contrast. On the other hand, concrete decisions Truman made contributed greatly to his unpopularity. These included the United States's less-than-stellar performance in the Korean War and Truman's firing of the very popular World War II hero, General MacArthur. Another unpopular decision Truman made was to have the US government take over the US steel mills in 1952 out of fears strikes and other union actions would disrupt the nation's steel supply during the Korean War. Further, Truman was blamed for initiating the loyalty oath for federal workers that led to the McCarthy witch hunts. Added to this, Truman had a personal manner that was sometimes less than appealing to voters.

History has been much kinder to Truman, rating him an effective president during a difficult period in US history.