Turnout for Tuesday's primary election was 33.4 percent in Oregon, the lowest on record. But Oregonians need not scold themselves for a lack of civic engagement. The turnout percentage was down because voter registration is up, and because many of the state's newly registered voters choose not to join a political party. Low-turnout primary elections are likely to become the norm in Oregon.

The number of registered voters in Oregon has grown by 570,000 since 2014, a 27 percent increase. Much of that increase is due to the Motor Voter law that took effect in 2016 — anyone who obtains or renews a driver's license in Oregon is automatically registered to vote. Motor-voter registrants are not affiliated with any political party unless they choose to take an additional step. Most do not, and as a result the already rising number of non-affiliated voters has grown to 31 percent of the electorate, surpassing the Republican Party (26 percent) and closing in on the Democratic Party (36 percent).

Non-affiliated voters didn't find much to capture their attention on the May 15 ballot: They could vote for labor commissioner and in a couple of state appellate court races, and that's it. In some parts of Oregon, including much of Lane County, non-affiliated voters could mark their ballots in non-partisan county commission and city council races. They could also vote on local ballot measures and property tax proposals such as Eugene's proposals for parks and a city auditor. That explains why Lane County's 36.1 percent turnout exceeded the state average.

Despite the anemic participation rate, the number of ballots cast on Tuesday — 895,574 — was the highest ever for an Oregon primary election that did not feature a presidential contest. Part of that is due to population growth. But it's also due to the surge in registration. Even a low turnout by members of an expanded voter pool yields a lot of ballots to be counted.

There are ways to increase primary election turnout — one would be for the major parties to open their primaries to non-affiliated voters. The Independent Party of Oregon has done that, though the secretary of state's office didn't make it easy for non-party members to obtain an Independent ballot and didn't publicize the option of requesting one. But even without open primaries, turnout in future off-year elections will rise if there are hotly contested races for U.S. Senate or gubernatorial nominations.

Voting is a civic virtue — and despite Tuesday's low turnout, it's a virtue that is very much alive in Oregon. In the 2016 general election, 80.3 percent of the state's registered voters cast ballots, and the total number of votes exceeded 2 million for the first time.