The U.S. Census Monitoring Board estimates that 76,819 people in Cook County were not counted in the 2000 census. That’s nearly enough bodies to fill Wrigley Field twice.

People go uncounted for a variety of reasons — they’re undocumented and afraid of government retribution, unwilling to relinquish personal information or unaware of what’s at stake in the count.

So what is at stake?

The short answer: your piece of a $400 billion annual pie.

The U.S. Census Bureau says the federal government distributes $400 billion annually to local, state and county governments, based on the population count.

That’s more than $4 trillion over 10 years, according to the bureau.

“The size of your slice depends on how many people live in your community,” said Lydia Ortiz at the Chicago Regional Census Center. “You know that pothole you have on your street? Well, there will be more money to fix that pothole if you get counted.”

Those $400 billion dollars fund roads, health care, education, law enforcement and other social services.

“It’s to the benefit of each person to be counted,” Ortiz said.

According to a new report from researchers at the Brookings Institution, Illinois received $19.1 billion of federal funding in 2008 that was tied to census numbers. At least $12.6 billion of that total went to Chicago. Those figures would have been higher, had every person in the city and state been counted.

Say in a 100-person community, only half respond to the census. The federal government will give the community a slice of pie only big enough to feed 50 people. But all 100 people — including the fifty who weren’t counted — will have to share the slice. That distribution model will be used to divide up monetary “pies,” on the federal, state and local level, until the next census count in 2020.

Cook County is estimated to have been one of the biggest financial losers nationwide because of an undercount in 2000.

The U.S. Census Monitoring Board estimates in a congressional report that Cook County missed out on about $200 million from eight major federally funded programs between 2002 and 2012.

That’s an awful lot of pastry.

County undercounts also affect how funds are distributed throughout the state. The monitoring board’s report argues Cook County has significantly higher undercount rates compared with other Illinois counties. So when it was time to divide state resources, Cook County got shortchanged.

The board says the 58 largest undercounted counties in the nation lost about $3.6 billion collectively after the 2000 census. Broken down, that’s $2,913 lost for every person not counted, and all because that person did not fill out a census form.

By March 8 the census office was scheduled to have mailed an informational letter about the 2010 count. About a week later, residents should find an official census questionnaire in their mailboxes.

If the census office has not received a response by late April, a household will be added to a “non-response follow-up list.” And in May, a census worker on could be on the doorstep.