Voter registration among people 29 and younger increased across battleground states after the February 14 Parkland shooting, according to an analysis by TargetSmart.

Why it matters: This analysis suggests millennial voters could have an increased impact on the midterm elections, particularly on the issue of gun control, in states that could decide control of Congress.

The state of play: Pennsylvania, which has competitive races at every level, saw a 16-point increase in youth voter registration over the last five months.

New York and Virginia, which have numerous competitive House races, had increased of nearly 11 points.

Indiana, which has one of the most vulnerable Democratic senators, had a 10-point increase.

Arizona, where Republicans are fighting to keep an open Senate seat, had an 8-point increase. Florida, where the shooting happened, also saw an 8-point increase.

The bottom line: Now that they're registered, they actually have to show up to vote.