More than 42 million Americans have cast midterm ballots, and interesting demographic data shows who is voting.

According to the University of Florida Election Lab, early midterm turnout is similar to the 2018 "blue wave." The lab said enthusiasm appears to be on the Democrats' side.

Michael McDonald, a University of Florida political scientist, said the U.S. could be headed toward record turnout."It's possible that we will beat the 2018 turnout rate. That was the highest turnout rate for midterm elections since 1914. But there are uneven patterns of turnout," McDonald said.