"Out of 90,000 ballots we mailed out, we received 32 percent back," she said. "That's telling."
Primary participation corroborated evidence from last fall's municipal elections. Both Cottonwood Heights and West Jordan conducted their elections entirely with mail-in votes and came up with similar responses three times more votes were cast than in a comparable year of voting at polling places.
Swensen expects more cities to follow suit in the 2015 municipal elections, leaving enough people countywide feeling comfortable with the process that it could be implemented if the council gives its approval for all or part of the 2016 general election.
"I know some people like to go to their neighborhood polling place on Election Day, so it will take some time for them to get over that," she added. "But this has been the trend."
Swensen also was pleased with the success of a pilot project to allow people to register to vote on Election Day.
She said 66 people signed up June 24, including 17 senior citizens who moved to Salt Lake County recently and had not been able to register before. Another 30 were under 30 years of age, almost exclusively first-time registrants.
While the primary turnout was "small and disappointing," Swensen said, "It was not the smallest we've ever had." Only 6.74 percent of registered voters cast ballots in a pair of 2002 Republican congressional primaries, including one between John Swallow and Tim Bridgewater.
Swallow won, only to lose in the general election. Last year, a scandal forced him to step down as Utah attorney general.
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Voting by mail
Seven Utah counties went to vote-by-mail during the recent primary election, including Salt Lake County's neighbor, Davis County.
The number of Davis County voters participating June 24 was the highest in a county primary election in 20 years, said Brian McKenzie, elections manager. Turnout percentage is nearly impossible to calculate because, aside from a couple of school-district races, only Republican contests which exclude Democrats were on the ballot.
But McKenzie said it appears that vote-by-mail has made a positive difference in turnout. Some 26,456 voters cast ballots in the recent primary nearly 3,400 more than in the previous biggest primary turnout for the 2010 runoff between GOP Senate hopefuls Mike Lee and Tim Bridgewater.
Other counties adopting vote-by-mail this year were Beaver, Duchesne, Garfield, Grand, San Juan and Sevier.