Turnout is on the upswing since the Democratic party in Kansas switched from a presidential caucus to an all-mail primary.
With a few days of voting left to go, the party already has processed over 138,000 ballots, The Kansas City Star reports.
That is compared to a turnout of just over 39,000 voters in 2016.
Voters have until Saturday to get their ballots to party headquarters.
The spike in turnout occurred despite Senator Bernie Sanders dropping out this month, and endorsing former Vice President Joe Biden, now the party’s presumptive nominee.
Every registered Democrat in the state – more than 400,000 people – received a ballot.
Democrats made the decision last year to drop the caucus format, which required voters to meet and split into groups.
The party already was taking steps to encourage mail voting, but switched to an entirely mail-in ballot after COVID-19 raised safety concerns.