Voters at the Palisades High School polling site in the 2012 presidential election in Pacific Palisades, Calif. (MICHAEL NELSON/European Pressphoto Agency)

ONLY 42 percent of eligible Californians voted in the last federal election. That was above the national turnout, 36.4 percent, but nothing to brag about. So good for California, which is joining Oregon in taking an obvious step toward encouraging turnout: automatic voter registration.

This year Oregon lawmakers decided that people getting driver’s licenses or state ID cards will be registered to vote unless they opt out. No one has to go on the voter list, in other words, but the default setting is registration. The law also makes it easier to keep voter rolls updated, as people must keep the information on their driver’s licenses current. State officials expect to automatically register a large fraction of the 800,000 unregistered eligible voters.

Next to California, though, Oregon’s numbers seem measly. The Golden State has nearly 7 million unregistered eligible voters and no less of a driving culture. California’s Senate wants to reach many of them with a bill it passed last week adopting Oregon’s basic system.

It is true that some people never come in contact with the DMV. A logical next step for California would be to require any state agency collecting the necessary information to send it along to the voter rolls.

It is also true that registering people doesn’t guarantee they will vote. But that doesn’t mean the government shouldn’t nudge them to join the voter rolls, anyway. The policy costs virtually nothing in money or individual liberty. It is worth doing even if the effects on turnout are marginal. Over time, it should lead people to assume that they are registered and that voting is an option, even if they start paying attention only on Election Day.

Other states should follow. But none should treat this modest reform as a cure-all, particularly in states that maintain other unnecessary barriers to voting. California, for example, already allows people who go to the wrong polling place to cast a provisional ballot, but other states do not. In fact, California and every other state should allow any resident to vote at any precinct without resorting to provisional ballots. That’s another obvious step, along with expansive early voting opportunities, better-run polling places, early registration at age 16 and an end to cynical voter ID laws. If the states don’t get on with such changes, Congress should mandate them for federal elections.

Neither California nor the country at large will ever reach full turnout. But there are sensible ways to get a lot closer.