(AP Photo/Orlin Wagner)

Young people are much less likely to vote, a fact that could weaken their political power.  Some states have attempted to bring more young people into the electorate by allowing them to “preregister” to vote before they turn 18. Those who pr-register automatically become registered when they do turn 18.

Does this actually work?  New research suggests that it does.

Political scientists John Holbein and Sunshine Hillygus investigated the impact of preregistration in two different ways.  First, drawing on the Current Population Survey, they compared trends in turnout among 18-22-year-olds from 2000-2012 in states that implemented preregistration and those without.  The apparent impact of preregistration was to increase the turnout of young people.  Depending on the particular statistical model employed, the increase ranged between 2 points and 13 points.

Holbein and Hillygus confirm this finding using 2012 turnout data from Florida, a state that has had preregistration since 1990.  About 8 percent of registered voters in Florida today were originally preregistered.

Holbein and Hillygus focus on 21- and 22-year-olds.  Because of their birthdate, some of these young people were eligible to vote in 2008, but others were not.  Using what is called a regression discontinuity design, Holbein and Hillygus show that those who turned 18 after Nov. 4, 2008 were more likely to preregister to vote than those who turned 18 before Nov. 4 and were already eligible to vote..

Their approach then assumes that the mere fact that you turned 18 on, say, Nov. 3 compared to Nov. 5 is essentially random.  Thus, they use birthdates as a way to estimate the impact of preregistration on turnout.

They find that preregistration did increase turnout among these young voters in 2012.  Below is the graph showing the “discontinuity”: the increase in turnout among those born after Nov. 4, 1990 — that is, those who would not have been eligible to vote in 2008 and were therefore more likely to preregister:

Graph by John Holbein and Sunshine Hillygus

You might think that anything that increases the turnout of young people would inevitably benefit Democrats, since young people lean toward the Democratic Party.  But that is not what Holbein and Hillygus found.  Although preregistration tended to add more Democrats than Republicans to the rolls — simply because more young people registered as Democrats — it actually reduced the Democratic advantage among those young people who actually voted. Holbein and Hillygus write:

We estimate that approximately 37% of partisan voters mobilized by preregistration in 2008 were likely to vote Republican in 2012; in comparison, only 32% of young voters in Florida voted Republican in 2012.

As Holbein and Hillygus note in conclusion, many proposed ways to increase turnout fail to live up to expectations.  But preregistration seems to be an exception.