Three surveys recently released are now showing significant increases in the number of people insured in just the last six months (September 2013 to March 2014), roughly showing the same effect:

All of these are person-level surveys, and not of the really large samples we like to use to study the uninsured over time (e.g., American Community Survey, Current Population Survey).  So this probably should be treated with some caution.  On the other hand, the results are strikingly similar.  Also, on the other hand, the results do not include the end of March, when the marketplace enrollments closed.  Finally, the Medicaid enrollments continue year round, so we are still going to continue to see the effects of the Affordable Care Act roll out for a while longer.  Some states are still debating Medicaid expansion, so this also could improve the outlook.  

The bottom line however is that in a very short period of time (six months) we are seeing the uninsured rate drop by rather large amounts -- 15-20%.  That is simply unprecedented.  The factors contributing to this we will have to explore, and it appears not all of this is due to the ACA, but no doubt much of the change is due to the ACA, and that is good news, encouraging.