SALT LAKE CITY — More than a fourth of voters in Salt Lake County have mailed in their ballots, and thousands of voters continue to register, showing participation in Utah's 2018 midterms may surpass that seen in the last presidential election.

Sherrie Swensen, Salt Lake County Clerk, said the rolls of active voters in Utah's most populous county have already swelled beyond where they were in 2016.

"In the presidential election at the very end of the registration period we had 510,000 active registered voters in Salt Lake County. We have already surpassed that," Swensen said.

On October 24 of 2016, the Salt Lake County Clerk had received 83,587 mailed in ballots. On October 24, 2018, Swensen said she had received 138,000 mailed in ballots.

Registrations are also on the rise. Swensen said the county is getting hundreds of new registrations every day, amounting to 22,000 new voters in the last month.

Statewide, registrations are up overall, but the biggest surprise is a declining number.

There are 17,755 fewer voters registered as "unaffiliated."

The "unaffiliated" category is second only to Republicans as the party category for Utah voters, numbering 606,263. Republicans have 730,805 voters and Democrats have 200,881.

In the last two years, Republicans gained 25,331 new voters and Democrats gained 20,860.

Utah's other registered parties also gained members. Most notably, the Independent American party gained nearly 14,000 members, amounting to growth of about 37 percent.

Swensen and Utah County Clerk Bryan Thompson credit ballot propositions for the bulk of voter interest. In particular, Swensen said Proposition 2 legalizing medical marijuana is what she has heard about the most from voters.