Congress uses census data to allocate funds under various federal grant programs to state governments. Many state-funded grant programs also rely on census data. Because the annual population estimates use the decennial census counts as a base, if a community's population is undercounted in the decennial census, these funds get misallocated for an entire decade.
The federal govenment relied on Census data to provide over $17.9 billion in funding to Indiana for fiscal year 2016 from the 55 largest federal spending programs. Although each program's funding formula is complex (and in most cases unique), Indiana's $17.9 billion in funding roughly equates to $2,710 per person each year.
For more details, see the Indiana Fact Sheetand the Counting for Dollars project page at the George Washington Institute of Public Policy.
Of course, federal funding is just part of the picture. Many state agencies distribute funds to local areas based on local population counts: