The deadline to sign up for health insurance under the Affordable Care Act, also called Obamacare, passed Sunday, Feb. 15, 2015, but some states offered extensions. Above, Karima Williams (right) and Marjorie Brown (second from right) of DC Health Link assist barber Cornel Henry (left) with health insurance information in Washington, Jan.24, 2015. Reuters/Jonathan Ernst

Sunday's deadline to sign up for health insurance under the Affordable Care Act, also known as Obamacare, passed as many states held last-minute sign-up campaigns and some even extended their deadlines after a technical glitch Saturday affected some people's ability to sign up. States and local areas reported holding call-a-thons and enrollment events to encourage people to buy health insurance, efforts that were thwarted in part by technical glitches on the federal website, HealthCare.gov, as well as some sites for state-run exchanges.

In the Northeast, a winter storm over the weekend also hindered sign-ups at the last minute. Rhode Island, which runs its own marketplace, extended its deadline, giving people until Feb. 23 to sign up for a plan. Last week, California's exchange, Covered California, said it would give those who started applications by the national deadline of Feb. 15 until Feb. 20 to complete them.

Local and federal government officials encouraged people to sign up for health insurancelast week, reminding them that if they didn't sign up by Sunday's deadline, they would notlikely be able to do so again until October. But technical glitches frustrated some who tried to sign up on Saturday. HealthCare.gov had problems with the income verification portion of the sign-up process, and officials spent about six hours working on the issue before it was fixed. Some state exchanges reported similar issues. Katie Hill, the Department of Health and Human Services (DHHS) press secretary, explained the problem as being due to "intermittent issues with external verification sources."

New York state gave New Yorkers who signed up but did not complete the application for health insurance by Feb. 15 two extra weeks to finish enrolling in a plan. By February 4, in New York, more than 2 million had signed up for insurance during the 2015 open enrollment period, which began November 15, 2014, and ended on Sunday. Of those, 1.4 million had enrolled in Medicaid.

On Monday, the HealthCare.gov blog suggested that extensions may still be possible after the end of the open enrollment period for those who either tried to enroll before Sunday but could not due to website glitches or call-center delays, or for those who had sent paper applications by mail by the Feb. 15 deadline but had not completed the enrollment process. "We know many of you worked hard to enroll in a plan through the Health Insurance Marketplace," the site said. "Despite your best efforts, you may not have been able to complete your application and select a plan."

According to acasignups.net, a site that tracks Affordable Care Act enrollment numbers, nearly 10.5 million were confirmed to have enrolled in a health care plan as of Saturday, and 11.3 million were estimated to have signed up. In the last few days before the Feb. 15 deadline, sign-up numbers drastically increased. The DHHS expected 9.1 million to sign up during the 2015 open enrollment period.

DHHS said it had 80,000 concurrent visitors to the HealthCare.gov website at 8:30 p.m. Sunday, the highest number since Dec. 15. It also reported that the HealthCare.gov call center, which can be used to start applications for health care coverage as well as compare plans or ask questions, fielded over 250,000 calls on Sunday. The deadline for signing up via the federal marketplace was 2:59 a.m. Eastern Time Monday, although some state-run exchanges posted different deadlines.