Every 10 years, the U.S. Census Bureau begins the process of counting every person living in the country, in part, to ensure that federal dollars are properly being allocated to states. The census guides and informs how much in federal funding Illinois, and every state, receives. To put it in context, the 2010 census results drove the allocation of $34.3 billion in federal funding, according to a report by the George Washington Institute of Public Policy. Yes, that's a billion with a “B.”

The federal government has counted its people since 1790. So why has the process of collecting U.S. population data become so difficult this time around?