Four others attended college but dropped out before finishing their degrees: James Monroe, William Henry Harrison, William McKinley and Harry Truman. (Harrison dropped out of two colleges, Hampden-Sydney College and the University of Pennsylvania, to embark on a military career. McKinley dropped out of Allegheny College, but many years later, after serving in the Army during the Civil War, he studied law at Albany Law School in New York.)

At the other end of the spectrum, two men were college presidents before they were United States presidents: Woodrow Wilson (of Princeton) and Dwight Eisenhower (of Columbia). William Howard Taft was dean of the University of Cincinnati Law School. Thomas Jefferson founded the University of Virginia after leaving office, became its first rector (essentially its president), and was succeeded in that role by James Madison.

Truman has been the only president since 1901 without a bachelor’s degree, but two consecutive vice presidents in the 20th century also lacked one: Charles Curtis (who served under Herbert Hoover) and John Nance Garner (under Franklin Roosevelt). As was common in an earlier era — several 19th-century presidents also did this — Curtis and Garner became lawyers despite having little formal education, by studying in their spare time and taking the bar exam.

There were three unsuccessful 20th-century presidential nominees without degrees: James Cox, the Democrat who lost in 1920 to Warren Harding; Al Smith, defeated by Herbert Hoover in 1928; and Barry Goldwater, a University of Arizona dropout, who lost to Lyndon Johnson in 1964.

Perhaps the most recent significant presidential contender without a college degree was Senator Paul Simon of Illinois, who unsuccessfully sought the Democratic nomination in 1988. He dropped out of Dana College in Nebraska in 1948 to go into the newspaper business. Nevertheless, Mr. Simon looked like a scholar, with his trademark horn-rimmed glasses and bow ties, and became one after leaving the Senate, as the founder of a public policy institute at Southern Illinois University.