Extending coverage to the uninsured was one of the central justifications for President Obama's health care law. But with the six-month open enrollment period coming to a close at the end of the month, it remains unclear how many of 4.2 million private insurance sign-ups claimed by the Department of Health and Human Services came from the ranks of the previously long-term uninsured.

Some have speculated that the bulk of the new sign-ups have come from those with previous insurance plans that got cancelled because of Obamacare, which would mean fewer Americans than expected are actually gaining coverage as a result of the law who otherwise wouldn't have it. HHS hasn't released data on the prior insurance status of those selecting a plan through one of the exchanges, leaving health care policy analysts to parse various surveys looking for clues.

So I decided to do a little experiment. All else being equal, I postulated, if Obamacare sign-ups were mostly coming from the ranks of the uninsured, then states with the highest percentages of uninsured should be signing up the most people on a population-adjusted basis.

I took the latest sign-up figures from HHS for the Oct. 1-March 1 period for each state and divided that by state population, based on the latest Census estimates. That gave me a list of every state, ranked by the proportion of the state population that signed up for a plan through one of the exchanges.

I then compared that list to Kaiser Family Foundation data on the percentage of uninsured by state in 2012 and boiled my findings down to the table below, which lists the states with the top 10 percentages of uninsured before Obamacare's exchanges opened, and then shows where those states rank on Obamacare signups by percentage of the population.

State Ranking by percentage of uninsured Ranking by percentage of state population

signed up for Obamacare Texas 1 27 Nevada 2 28 New Mexico

3 43 Florida 4 4 Louisiana 5 32 Georgia 6 14 Alaska 7 35 California 8 3 Montana 9 5 Arkansas 10 34



As you can see, Texas, the state with the highest percentage uninsured, ranked 27th in terms of adjusted Obamacare sign-ups. Overall, seven of the states with the top 10 uninsured percentages did not crack the top 10 states for Obamacare sign-ups by percentage, and six of the states didn't make the top 26. The exceptions were Florida, California and Montana, which were on the top 10 of both lists.

To be clear, I'm not saying this proves anything definitively, as there are plenty of variables involved. This analysis does not include Medicaid enrollment, for instance, because about half of the states aren't participating, so the numbers wouldn't be comparable. Additionally, Florida and California are among the nation's largest states, so they'll drive national data more than, say, New Mexico.

But if Obamacare is to make a more significant dent in the number of the uninsured, it’s probably going to need deeper penetration into those states with the highest rates of uninsured residents.