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The difficulty in getting voters to show up for a runoff election is a big problem in Texas. There are hotspots around the state that might engage more voters, but generally speaking, it’s hard enough to get voters to the table once —and harder still to get them to come back for seconds.

Turnout in the March primaries was mediocre. According to the Texas secretary of state, 10.2 percent of the state’s 15.2 million registered voters cast ballots in the Republican primary, while 7 percent showed up for the Democratic primary. Together, those primaries attracted a little over 2.6 million voters.

What does that mean for this month’s runoffs? To start with, there’s only one statewide race on the Democratic ballot — the one for governor — and no statewide race on the GOP ballot. In many parts of the state, that takes away a big reason to cast a ballot on May 22 or during early voting. On the Republican side, local races from Congress down to constable could be on the ballot — most of them low-draw affairs.

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The last gubernatorial-year primaries in 2014 open a window on this. In the primaries that year, 10 percent of registered voters showed up for the GOP primary and another 4.1 percent came to the Democratic primary.

For anyone who measures civic health by voter turnout, the turnout for the 2014 runoffs would have prompted a call for an ambulance: 5.5 percent turned out for the Republican primary runoff, while 1.5 percent turned out for the Democrats.

What was on that ballot? Democratic voters decided two statewide races, making David Alameel their nominee for U.S. Senate and picking the unknown Jim Hogan over the all-too-well-known Kinky Friedman as their nominee for Texas Agriculture Commissioner. In most parts of the state, those were the only two contests on the ballot.

On the Republican side, four statewide races drove turnout — for lieutenant governor (Dan Patrick beat David Dewhurst), attorney general (Ken Paxton beat Dan Branch), agriculture commissioner (Sid Miller beat Tommy Merritt) and railroad commissioner (Ryan Sitton beat Wayne Christian). All that activity is one big reason their second-round numbers were a bit healthier than the Democrats’ second round turnout.

In 2010, the gubernatorial election year before that one, the Democrats had no statewide races. Voters turned out the way you would expect in that situation: They stayed home. Turnout was 5.2 percent in the primary and dropped to 0.21 percent in the runoff.

Republicans had only a Texas Supreme Court race (Debra Lehrmann beat Rick Green) on their statewide runoff ticket. Their turnout that year dropped to 2.6 in the runoff from 11.4 percent in the primary.

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The overall turnout numbers are higher in presidential election years, but the runoff slumps are just as pronounced.

In 2016, with only one statewide race on their runoff ticket (Grady Yarbrough beat Cody Garrett in the race for railroad commissioner), Democratic turnout was 1.3 percent, down from 10.8 percent in that year’s March primary.

On the Republican side, turnout fell to 2.6 percent in the runoff, down from 19.9 percent in the primary. The draws in the first round were big: The GOP had not yet chosen a presidential nominee, and Texans turned out to vote on a list of candidates that included Donald Trump, Ted Cruz, Marco Rubio and all those others.

The runoff attractions were a lot less than dramatic, with Wayne Christian beating Gary Gates in a bout for railroad commissioner and two judges — Mary Lou Keel and Scott Walker — winning nominations for the Texas Court of Criminal Appeals.

Those aren’t generally the kinds of races that get many people talking — or voting — and that’s why the drop was so big.

The 2012 presidential primary year wraps up this quick survey. On the Republican side, a hotly contested U.S. Senate race drew national attention for the first time to a political nobody named Ted Cruz, who bested Dewhurst. Christi Craddick won a spot on the Texas Railroad Commission and John Devine beat David Medina, an incumbent, for a spot on the Texas Supreme Court.

Those are better-than-average draws, and turnout in the runoff was 8.5 percent, compared to 11.1 percent in that year’s Republican primary. Not bad, as these things go.

On the Democratic side, the 2012 primary turnout was 4.5 percent, about the norm for the state’s smallest major party. The runoff turnout was weak, with only a lackluster U.S. Senate race (Paul Sadler beat Grady Yarbrough) on the statewide tickets. Only 1.8 percent turned out for that.

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This year isn’t a presidential year, and there’s just that one Democratic race on the statewide runoff ballot. Hope for a big turnout, but don’t count on it.