Around the 1964 presidential election–back when “Mad Man” Don Draper was still smoking Camels–men and women began to gradually diverge in their political views and behavior. We call this the “gender gap.”

Political scientists Karen M. Kaufman, John R. Petrocik and Daron Shaw, in their book Unconventional Wisdom: Facts and Myths about American Voters, observe this split “that began more than forty years ago has grown into a significant and enduring political division.”