James Buchanan – 139.6
The 15th president didn’t make significant strides forward from his predecessor. The majority of historians will recall that James Buchanan set himself some lofty objectives when he became president. During his presidency, Buchanan promised to achieve the heights of George Washington’s political career. President James Buchanan has been added to the list of presidents who had an IQ of 139. Unfortunately, he was unable to complete the journey.