Lyndon B. Johnson – 140.6
After JFK’s death in 1963, this president became known for taking over. We’re still on the lower end of the list of presidents, with an IQ of 140.6. Lyndon Baines Johnson, popularly known as LBJ, is the 36th President of the United States. He served from 1963 to 1969, leaving a lasting legacy. He is praised for his efforts to drive the country forward in a number of important areas. During his presidency, he enacted civil rights, gun, and welfare legislation. Not to mention his part in establishing Social Security and extending Medicaid and Medicare.