There have been serious problems with the Census Bureau's estimates in the past, and the most recent numbers continue to give cause for concern:
"... Indeed, for the recently released 2012 vintage municipal estimates, they went back to using a real estimating methodology instead of the simple allocation approach from 2011. However, as with the 2000s, these are showing strong municipal population growth in places where that would represent a major discontinuity with the actual decennial Census results from the 2000-2010, and from economic conditions.
How is it that cities, after a disappointing 2000s where some places actually underperformed versus the 1990s, in an economy that has been recessionary to sluggish the entire post-2010 person and in which the housing market that triggered the crash has also yet to recover, that these growth rates are possible? It’s certainly eyebrow-raising at a minimum."