According to Political Data Inc., the number of ballots returned between Sept. 24 and Oct. 23 make of 29 percent of the state's total ballots.
More than 3.5 million of the returned ballots are from registered Democrats in California, while nearly 1.4 million are from registered Republican, according to Political Data Inc.
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Californians 65 and older lead the state with the highest number of returned ballots so far, at roughly 2.3 million, accounting for 47 percent of the total ballots returned.
The 18 to 34 age range ranks lowest, with about 1.1 million ballots returned as of Oct. 23, the political data shows.
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Political Data Inc. reports more than 15 million ballots are still outstanding in California with just days until Election Day.
As Nov. 3 nears, Californians can now vote at arenas and concert venues in several counties, including Staples Center in Los Angeles, the Golden 1 Center in Sacramento, the Bill Graham Civic Auditorium in San Francisco and the Cow Palace in Daly City.
The Staple Center and Golden 1 Center opened Saturday as voting centers.
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The Bill Graham Auditorium will be open Saturday and Sunday and Oct. 31, Nov. 1 and Nov. 3. The Cow Palace will be open for voting from Oct. 20 to Oct. 24.
All registered voters in California should have received their mail-in ballot in early October.
Ballots will have prepaid postage and can returned at any time in California, including on Election Day.
A ballot can be received as late as Nov. 20 and it will still be counted, as long as it's postmarked no later than Nov. 3.
Californians can learn how to track their 2020 ballots here.
Get the latest stories and videos about the 2020 election here.
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