INDIANAPOLIS | Fewer Hoosiers voted in the May 6 primary than in any statewide election over the past quarter-century, and possibly ever.

Just 13 percent of Indiana's 4.57 million registered voters cast a ballot last month, according to Secretary of State Connie Lawson.

It's the first time since 2000 -- when turnout totaled 19.53 percent -- that primary election participation dipped below 1 in 5 registered voters.

As recently as 2008, the year Barack Obama and Hillary Clinton battled for Indiana's Democratic convention delegates, primary election turnout was 40 percent.

But with no presidential, U.S. Senate or governor's race on the primary ballot this year, it seems most Hoosier voters decided to stay home.

Still, a similar 2002 primary without any marquee races still managed to draw 22 percent of registered voters to the polls.

In Lake County, 44,752 residents cast a ballot out of 348,561 registered voters (13 percent). Turnout in Porter County was 11 percent; LaPorte County recorded 13 percent.

Contested Republican and Democratic primaries for a state Senate seat helped push turnout to 20 percent in Newton County. But in neighboring Jasper County, which is in a different Senate district, turnout reached just 8 percent.

The 13 percent statewide turnout is the lowest for any primary election since 1990, according to state records.

The secretary of state's office did not immediately have access to primary election turnout data prior to 1990. However, midterm general election turnout between 1962 and 1990 averaged 60.2 percent, compared with 41 percent in 2010, so primary turnout likely also was higher during that period.

Lawson said voter turnout in May probably was better than what the numbers show, because she suspects the percentages were skewed by outdated voter registration records.

"I believe our actual voter turnout numbers may be higher than 13 percent," Lawson said. "We are currently in the process of updating our voter list, which will give us clear data on Indiana's real voter turnout numbers in future elections."

As part of that process, all registered Indiana voters this month are receiving postcards aimed at identifying outdated and inaccurate voter registration information.

Voters whose postcards are returned as undeliverable will get a follow-up letter by first-class mail requesting they update their voter registration record.

Eventually, inaccurate, nonparticipating registrants will be purged from the state's voter rolls.