This comes from Avalere Health, a consulting firm that has crunched the numbers.
Avalere has worked backward from a Congressional Budget Office projection that 7 million people will enroll in the exchanges in 2014 and estimated that these 14 state-based marketplaces should account for 1.4 million of those sign-ups.
It's worth noting that these figures aren't exact; some states count enrollment differently. The White House is set to release its own data on health plan enrollment later this week, for both state-based and federally-run exchanges. Most of these numbers above represent enrollment in private plans, although some states, like Rhode Island, don't break that figure out from Medicaid enrollment.
The other question this begs is: Is 3 percent a good total for the first month of open enrollment? That's a bit hard to know, given that this is the country's national take at expanding private health coverage to millions of Americans. On the one hand, if the expectation was for enrollment to continue apace, this would be horrible news.
That is, luckily for the administration, not the expectation. Most health policy experts predict that enrollment will move faster in November and December, as we get closer to the Dec.15 enrollment deadline for January coverage. Massachusetts, as the White House points out pretty much any chance it gets, only had 0.3 percent of its first year-enrollment in the first month. This is not to say that the Avalere data predicts 70 million enrollees in year one -- we don't have enough uninsured people to make that happen -- but that 3 percent enrollment in month one is probably not doom.
Sarah Kliff will be answering questions about the health care law on Reddit at 1 p.m.