A big milestone in the release of federal data will come on Wednesday when the U.S. Census Bureau releases results from two surveys that are widely used to estimate the number of people in the U.S. with and without health insurance.

The Bureau will release estimates from the Current Population Survey/Annual Social and Economic Supplement (CPS/ASEC) and the American Community Survey (ACS).  The former survey provides national estimates of insurance coverage with breakdowns by demographics, income and other characteristics.  The latter survey (ACS) provides breakdowns by state.

This is an important milestone because this is the first time the Census Bureau will be releasing estimates from calendar year 2014, which was the first year of widespread implementation of the Affordable Care Act (ACA), or "Obamacare".  Some provisions went into effect before 2014, and the provisions are still being implemented.  However, 2014 represented the opening of the Health Insurance Marketplaces (HIMs) and the expansion of Medicaid in about two-thirds of the states.  

There have been some non-governmental surveys that have been released to date that have shown very significant drops in the number of uninsured and percentage of persons who are uninsured (such as estimates released by the Urban Institute and Gallup) and some preliminary estimates released from the Health Insurance Survey (HIS).  

However, for years the CPS has been used as a quasi-official source for estimates of the uninsured in the U.S., and in latter years the ACS.  Prior to the implementation of the ACA, estimates form these surveys concluded that about 45-50 million people were uninsured (in 2012 and earlier) and in 2013 an estimated 42 million uninsured.

It is worth noting that the estimates that will be released on September 16 are for ANNUAL COVERAGE in 2014, and thus are a partial snapshot of the full effect of Obamacare's impact on reducing the uninsured.  That is because these estimates will not include any additional individuals who were covered in 2015.