Young Invincibles, a health care advocacy group for young people, said in a statement that the news out of California shows “that young adults are engaged and excited about their new options even at this very early stage in the enrollment process.” It noted that California was a crucial state for recruiting young people because 31 percent of those living there lacked health insurance.

Officials said that over 10,000 applications for coverage were now being completed each day, with more than 360,000 applications having been completed through Tuesday. Those numbers include people who are also eligible for Medi-Cal, California’s no-cost health insurance program for the poor.

Like many of the 16 states and the District of Columbia that are operating their own marketplaces, California’s health insurance website has run far more smoothly than the federal website, which handles the online enrollment for 34 states that declined to set up their own exchanges. In November, roughly 2,700 people were enrolling each day, California officials said. That is up from 700 people a day when the site opened last month.

The federal site has been plagued by technical problems since it opened on Oct. 1. In contrast to California, only about 27,000 people enrolled in private plans through the federal website in October, although enrollment reportedly picked up in the first half of November.

People who did not qualify for a subsidy enrolled in significantly higher numbers than those who did. The state reported that 4,852 people who selected a private plan in October were eligible for tax credit subsidies, which are based on income, compared with 25,978 who did not qualify.

Timothy S. Jost, a health care expert at Washington and Lee University, said the same pattern emerged in the federal marketplace statistics released for October. “I suspect this is reasonably well-off people who are losing coverage in the individual market and have found good coverage on the exchange,” he said.