Today Is California's Voter Registration Deadline (No, the DNC did not make this rule)
Monday is the deadline for anyone who is not registered to vote in California, but wants to vote in the June primary.
San Diego County Registrar of Voters Michael Vu said residents can register online at sdvote.com until midnight. Hard-copy registration forms must be postmarked or delivered to the registrar Monday. Forms are available at the registrar's office on Overland Avenue, or at any public library, post office or DMV office.
More than 77,000 new voters have registered in San Diego County since November 2016. Vu said the increase in voter registration is largely due to the many new independent voters, who now make up 29 percent of the county's registered voters. That's roughly equal to the number of people who are registered Republican. Democrats make up 37 percent of the county's registered voters.
http://www.kpbs.org/news/2018/may/21/monday-californias-voter-registration-deadline/