Andrew Johnson – IQ 138.9

After making a sudden entrance into the public eye as Abraham Lincoln’s running mate, Andrew Johnson was named as the country’s top leader in 1865. While his IQ score suggests that he was quite smart, the North Carolina man’s views and personal biases let many Americans down.

Johnson went on to become the first-ever President to serve in the Senate after leaving the White House in 1869. He had a surprisingly good run in the political arena, especially given that he had no background or degrees to back his candidature!