In 2006 Dean Simonton, psychology professor at University of California at Davis, finished researching the “intellectual brilliance” of 42 U.S. presidents.

Some presidents pre-dated modern IQ testing. So Simonton estimated their scores with personality traits referenced in their biographies that indicate an above-average level of intelligence ­‑‑ “wise,” “inventive,” “artistic,” “curious,” “sophisticated,” “complicated,” and “insightful.”

From that study, we compiled a list of the top 20 smartest presidents.  And where the current President (Donald Trump) ranks among them.