Despite record registration numbers, voter turnout lagged behind in Harris County

“Simply put, the rules make a big difference. If you make it more challenging to vote or you reduce the time that people have to vote, then turnout will be lower as a result,” Rottinghaus said.

In comparison

Harris County saw the lowest percentage of voter turnout since 2004.

“Competitive elections drive turnout, and we didn't have that many competitive elections in Harris County. It ended up being more competitive because fewer Democrats were voting,” Rottinghaus said. “But it didn't start that way, and that's really the thing that drives turnout.”

He added that some of the other bigger counties also don’t see higher turnout because the races tend to be one-sided or at least were perceived to be one-sided.

An outlier that could also help explain the low turnout is the rain on Election Day, Rottinghaus said.

“Maybe a lagging indicator, but as you know, it rained on Election Day morning and that has the tendency to reduce turnout,” Rottinghaus said.

A 2007 study from the Journal of Politics found that when compared to normal conditions, rain reduces voter participation in a U.S. election by a rate of less than 1% per inch. Data from the Harris County Flood Control District shows some areas of the county accumulated more than two inches of rain Nov. 5.

One more thing

Voter registration does not correlate to voter turnout, Rottinghaus said, as new voters are the least likely to vote.

“So what we find basically is that...increasing the number of registered voters doesn't mean you're going to increase the number of voters. That's been a common misconception,” he said.

Newly registered voters may turn out for further elections, just not the first election in which they’re registered, Rottinghaus said.