In 2006, psychologist Dean Keith Simonton ran every American president through a historiometric analysis and produced an estimated IQ for each one, from the low 130s to the low 150s. The results scramble almost every assumption about which occupants of the White House were the sharp ones, and the man who finishes at the top of the list lasted barely six months in office. Here is the full ranking, plus a fact about each president you almost certainly did not learn in school.
1. Ulysses S. Grant, Estimated IQ 130
Grant sits at the bottom of this ranking, though a score of 130 would still put him in the top few percent of the general population, so the label of least clever president deserves an asterisk. He graduated from West Point in 1843, built his reputation in the Mexican-American War, and finished the Civil War as the general who accepted Robert E. Lee’s surrender at Appomattox.
Voters sent him to the White House in the election of 1868, and at 46 he was the youngest man to take the office up to that point. He served two terms, from 1869 to 1877, and used federal power aggressively against the Ku Klux Klan under the Enforcement Acts. He also appointed the first African American and the first Jewish American to senior federal posts.