Americans Are Signing Up for Obamacare in Record Numbers

Despite a recent warning from former President Donald J. Trump, the front-runner in the race for the 2024 Republican presidential nomination, that he was “seriously looking at alternatives” to the Affordable Care Act, the latest surge in marketplace enrollment is a testament to the law’s enduring power.

Legislation passed earlier in the Covid-19 pandemic increased federal subsidies for people buying plans, lowering the costs for many Americans. The Biden administration also lengthened the sign-up period and increased advertising for the program and funding for so-called navigators who help people enroll.

“More and more people are realizing they can come onto the marketplace,” said Cynthia Cox, the director of the Program on the Affordable Care Act at KFF, a nonprofit health policy research group.

She added: “Just because the A.C.A. has been around for a while doesn’t mean people who need to sign up for it know how to do that.”

On Dec. 15 — the deadline to sign up for coverage that begins on Jan. 1 — nearly 750,000 people opted for a marketplace plan on It was the largest single-day total yet.

Dr. Benjamin Sommers, a health economist at Harvard who served in the Biden administration, said that improved outreach helped explain the record sign-ups. “I’m pleasantly surprised,” he said.

With years of increased subsidies, he added, “it might be this is the natural growth rate over a few years in a new policy environment.”

Kody Kinsley, the top health official in North Carolina, said that his state had gotten creative by using its efforts expanding Medicaid to also sign people up for marketplace plans.

“We’ve had a very broad educational and outreach campaign — with civic organizations, churches, navigators — built around expansion to educate folks about eligibility,” he said in a text message.

He added: “As part of that, we support folks to get coverage on the marketplace, if they’re not eligible” for Medicaid.

The open-enrollment period on runs through mid-January, ending at 5 a.m. Eastern time on Jan. 17. People who enroll by then will have coverage beginning in February.

Biden administration officials said that they were encouraging enrollees who were already covered through to continue shopping for plans, in case a new option turns out to be better and more affordable.

The Affordable Care Act’s marketplaces have become particularly valuable to the people losing Medicaid coverage this year after a federal policy that guaranteed coverage earlier in the pandemic lapsed in April.

The millions of people dropping off Medicaid rolls has contributed to the uptick in marketplace enrollment, Ms. Cox said, and to surges during normally sleepier periods outside open enrollment. (Certain life events, such as the sudden loss of other health coverage, allow some Americans to get new plans outside the open enrollment period.)

According to federal health officials, from March to September enrollment in marketplace plans increased by 1.6 million people, or 1.5 million more than during the same period last year.