The uninsured rate fell to 15.6 percent in the first quarter of the year, according to new Gallup data released Monday — the lowest it's been since 2008. And the rate has been falling since late last year, signaling that ObamaCare is indeed having its intended effect of extending insurance to more and more people. (The scale of the y-axis overstates the slope of the trend line, but you get the idea.)

Moreover, the rate fell precipitously in March, dropping from 15.8 percent at the month's outset to 14.7 percent come April. Such a steep drop is most likely an indication that many people raced to get insured right before ObamaCare's end-of-month enrollment deadline. And indeed, the administration reported that signups spiked in the month's closing days, pushing the total enrollments to 7.1 million.

Now, the drop alone doesn't mark the law as an unfettered success. It will be some time before the insurance marketplace adjusts to the increased customer pool, and enrollments are projected to rise ever higher over the coming years. But on a base level, the law is at least accomplishing its goal of insuring the uninsured, and the trend line looks favorable to its continued success.