Voting machines in Tennessee (AP Photo/The Commercial Appeal, Mike Brown)

The Indiana Secretary of State’s office announced Monday that 696,407 voter registration files were “inactive,” and if those voters don’t make it to the polls at least once in the next two years, their records could be removed completely.

Advocates contend the “voter list refresh project” will help make the state’s voter turnout data more accurate. Had these inactive files been removed in time for Indiana’s primary election in May, voter turnout would have been 17 percent instead of 13 percent, and 71 percent instead of 58 percent in 2012, Secretary of State Connie Lawson’s office said in a press release.

“I am committed to protecting the voting process here in Indiana by making sure that each county has accurate voter registration lists,” Lawson (R) said in a statement. “By updating these records or adding them to the inactive list, we are one step closer to getting a more accurate picture of voter turnout and protecting the integrity of our elections.”

More than 5 million postcards were sent out in two mailings by Lawson’s office since May asking voters to update their information. Only 47,493 postcards have been filled out and returned by voters from the most recent mailing, while about 450,208 have been returned from the post office with addresses marked undeliverable.

Voters with “inactive” voter registration files will still be eligible to vote up until 2016, but will have to vote or update their information to prevent having their records being removed from poll lists.