The Gallup-Healthways Well-Being Index, released Monday, found that 15.9 percent of U.S. adults are uninsured thus far in 2014, down from 17.1 percent for the last three months --- or calendar quarter--- of 2013.

That translates roughly to 3 million to 4 million people [who previously did not have health insurance, now] getting coverage.

Gallup said the share of Americans who lack coverage is on track to drop to the lowest quarterly level it measured since 2008, before Obama took office.

The survey found that almost every major demographic group made progress getting health insurance, although Hispanics lagged.
...
The Gallup poll is considered authoritative because it combines the scope and depth found in government surveys with the timeliness of media sampling. Pollsters interview 500 people a day, 350 days a year. The latest health care results were based on more than 28,000 interviews, or about 28 times as many as in a standard national poll.

The survey can be an early indicator of broad shifts in society. Gallup saw a modest decline in the uninsured rate in January, and now two full months of data indicate a trend is taking shape.

Gallup said the drop coincides with the start of coverage under the health care law on Jan. 1.