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.
Of course, federal funding is just part of the picture. Many state agencies distribute funds to local areas based on local population counts: