In the suburbs of Salt Lake City, there is a planned community called Suncrest that has turned out to be a good place to study voter turnout. Suncrest feels like one community, full of modern, single-family houses. But it straddles two different counties — Salt Lake and Utah. And in 2016, the two used different voting systems. Salt Lake County switched to mail-based voting, which meant that all registered voters would receive a ballot at their home a few weeks before Election Day. They could then mail it back or drop it off at a county office. In Utah County, by contrast, residents still voted the old-fashioned way. They had to visit their local polling place, Ridgeline Elementary School, on Election Day.
It was a natural experiment — with impressive results. Turnout in the Salt Lake County portion of Suncrest rose much more than in the Utah County portion. The convenience of voting by mail led more people to do so.
It wasn’t just Suncrest, either. In the 21 Utah counties that used mail voting in 2016, turnout was between five and seven percentage points higher than expected, according to a new study by Pantheon Analytics, commissioned by Washington Monthly magazine. That’s an enormous effect, as Amelia Showalter, the study’s lead author, pointed out to me. “Normally,” said Showalter, who advises campaigns, “we are thrilled if an intervention increases turnout by one or two percentage points.”