Voter turnout in statewide primaries so far this year has been historically low, even among states with procedures designing to make voting more convenient.

Overall, voter turnout among the 25 states that have held primaries is down 18 percent from the 2010 election, according a study by the Center for the Study of the American Electorate. There were almost 123 million age-eligible voters in these primary states, but only about 18 million of them voted.

What percentage of eligible voters voted in their statewide primary

The state with the highest turnout was Montana, with 26.3 percent of its eligible voters voting. The lowest was Iowa, with 9.7 percent.

Many states with voting policies designed to make the process more convenient experienced lower turnout than 2010, including the four states that offer election-day registration, eight of the 11 that have early in-person voting, and 11 of the 13 with no-excuse absentee voting that allows a voter to request an absentee ballot without stating a reason and vote by mail.

The only states where turnout was higher in 2014 than it was in 2010 were West Virginia, Nebraska, and North Carolina.

Curtis Gans, director of the Center for the Study of the American Electorate, wrote in the study that the findings show some measures taken to make voting more convenient have backfired.

“We have made it easier and easier to vote, at some risk, without having a positive effect on turnout,” he wrote. “The core problem of participation does not reside in the realm of procedure, but rather in motivation.”

Gans believes attack ads that lead voters to believe they have a choice between “bad and awful” has contributed to low voter turnout, as has a decline in faith in government, new voters who grew up in households where their parents didn’t vote, and technology that has, “made grazing the Internet a substitute for reading the news.”

He suggested states should adopt voting hours like those in New York, which run from 6 a.m. on election day to 9 p.m., “offering citizens a chance to vote on both ends of the work day,” and information pamphlets of the kind many western states send to voters that include descriptions of candidates and ballot measures.