The CTA’s budget deficit might, in some way, be your fault. But it’s not like anyone could prove it.

In May of 2000, then-CTA President Frank Kruesi announced that an undercount in the 1990 census cost the authority as much as $10 million in state and federal subsidies. Each person not counted in that census cost the CTA $5.11 a year, according to an authority press release.

That’s great information. But it’s a decade old. What happened during the last 10 years?

“We do not have similar information for the 2000 census,” said CTA spokeswoman Katelyn Thrall.

That’s too bad.

But perhaps we could estimate how much the CTA lost in would-have-been stipends because of any Chicago undercount in 2000.

According to the U.S. Census Bureau’s Web site, only 58 percent of Chicago responded to the initial mailing of the 2000 census, well below the state (73 percent) and national (72 percent) participation rates.

But that doesn’t mean only 58 percent of Chicago participated in the census.

“Oh, [the percentage of participation] is in the high 90s,” said Census Bureau mathematical statistician Phil Gbur. “We go back like six times to the household to get the information that we need. You have to make an effort not to respond.”

But it can’t really be possible that every single Chicagoan participated in the 2000 census. There must be some estimate as to how many Chicagoans abstained.

“No, we don’t have that information,” Gbur said. “I don’t think we have that estimate by place. I am not sure we even have it nationally.”

That is not going to help us estimate how much the CTA lost because of an undercount.

The CTA received a minimum of nearly $37 million from the Federal Transit Administration in 2009. This included money that went toward work on the Brown Line, the Circle Line project, and the Red and the Yellow Line extensions.

Unfortunately, the transit administration was unable to estimate or provide data for how much money the CTA missed out on because of any undercount in the 2000 census.

“While an undercount would affect the amount of formula transit funding received by CTA, we would not be able to determine exactly by how much at this time,” said Paul Griffo, the agency’s senior public affairs officer. “The reason for this is that most FTA formula funding programs include consideration of population as well as other factors, such as vehicle revenue miles and population density.”

If the FTA, CTA and U.S. Census Bureau don’t know the undercount in Chicago or the amount of money the transportation agency gave the CTA per person in Chicago – much less how much money the CTA missed out on because of an undercount – it seems unlikely that anyone does.

Where the three agencies agree is that if there were an undercount, the CTA would have missed a chance to get state and federal money.

“If folks don’t participate in the census, population data is going to be down and areas that rely on the CTA could see their services cut,” said Jim Accurso, media specialist with the U.S. Census Bureau’s Chicago office.

So, if you didn’t participate in the 2000 census, you did cost the CTA money. As to how much, no one seems to know. What is known is that the CTA doesn’t have money to spare. It has been working to reduce a $300-million budget deficit, and cut its service in February.

But census delinquents will have a chance to redeem themselves. The deadline for mailing back 2010 Census is today, April 1.