LOS ANGELES (KABC) -- Millions of California voters have cast their ballots by mail or dropoff in the days leading to Tuesday's election.

In Los Angeles County, more than 600 vote centers opened this weekend.

As of Monday, Los Angeles County officials estimate 1.7 million votes have already been cast - about 30% of the county's registered voters. L.A. County voters can cast their ballot at any vote center, regardless of where they live. There are a lot of races, so officials are urging voters to bring their mail-in ballots, which were sent to every registered voter.

L.A. County Registrar/Recorder Dean Logan says the sample ballots have a QR code that can be used for a quick check-in at the polling place.

In San Bernardino County, about 300,000 votes have been cast so far. In Riverside County, 460,000; Ventura County, 210,000; and Orange County, 780,000. For OC that's 42% of registered voters, the highest turnout so far in the region.

"We've been processing ballots since Oct. 8 so we've got people working yesterday, today staying on top of processing mail ballots, serving in-person voters," said Orange County Registrar of Voters Bob Page. "We increased the number of vote centers we had yesterday from 38 the first week up to 184 yesterday."