Forget the Gold Rush—California saw a flood of people enrolling in Obamacare after its deadline was effectively extended until Tax Day.
As of Tuesday, California had enrolled about 3.3 million in either private insurance plans or the state's version of Medicaid since Oct. 1, officials announced Thursday.
Of that total, the state's Obamacare exchange signed up nearly 1.4 million people in private health insurance plans by the close of open enrollment, officials said. That tally exceeds original projections by nearly 816,000 people.
"That is a huge number," said Peter Lee, executive director of the Covered California exchange, of the 1,395,929 official sign-ups since enrollment began Oct. 1.
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The remaining 1.9 million people enrolled in Medi-Cal, the state's Medicaid program, officials said. Unlike enrollment in private Obamacare plans, which is closed until next fall, enrollment in Medi-Cal is open year-round.
Lee said a significant number of people took advantage of the deadline extension that California offered people who had started applications for private plans by the original March 31 deadline, but had not completed their enrollment by then.
On Monday, 27,000 people enrolled in private plans, he said. On Tuesday, the last day people could enroll, 50,000 people signed up. That was a record for one day, he said.
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California is the leader in private Obamacare plan enrollment, by far.
About 29 percent of all people enrolled in California's plans were young adults between the ages of 18 and 34, officials said.
About 88 percent of the enrollees will receive a federal subsidy to offset the cost of their insurance premiums, and possibly their out-of-pocket health-care costs, according to Covered California.
And about 58 percent picked so-called silver plans, the second-least expensive type of plans offered on Obamacare exchanges.
Lee said that 85 percent of enrollees have paid their first month's premium so far.
He said he was pleased to see an increase in Latino enrollment, which had been a source of concern for the exchange, whose original enrollment numbers for that demographic had lagged.
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Latino enrollment increased by a rate of 30 percent in the last two weeks of enrollment, he said.
By the end of enrollment, about 28 percent of the sign-ups were from self-identified Latinos, he said.
The U.S. Health and Human Services Department is expected to release national Obamacare enrollment data later Thursday.
Like California and a number of other states that operate their own Affordable Care Act exchanges, the federally run Obamacare exchange HealthCare.gov extended its sign-up deadline through Tuesday for people who were "in-line" to enroll as of March 31, but hadn't completed their enrollment by then.
HealthCare.gov sells private Obamacare plans to residents of 36 states.
—By CNBC's Dan Mangan.