Did you remember that population data is only estimated between Census years? That means the closer we get to the actual Census count, the more difficult it is to accurately estimate an area's population. No, the estimators don't have a crystal ball and they sometimes over or under estimate population counts. Then, when an actual figure is available, it makes sense to re-estimate the previous years.
Well, the Census Bureau has just released their revised intercensal population estimates by county. Those of you who would like a clean data series from 2000 to 2010, can access those numbers here. Keep in mind that the Utah Population Estimates Committee will also be revising their intercensal estimates in upcoming months.