Where do Trump voters come from?

This Bell Curve shows the distribution of IQ in the US population.  Average IQ is 100.  Note that HALF THE POPULATION is below 100 and some of that 50% is well below 100.  The region to the left of 100 is where Republican voters come from.

A graph of a bell curve is labeled “Intelligence Quotient Score.” The x axis is labeled “IQ,” and the y axis is labeled “Population.” Beginning at an IQ of 60, the population rises to a curved peak at an IQ of 100 and then drops off at the same rate ending near zero at an IQ of 140.