Compared to the rest of the country, Chicago is lagging in its participation for the 2010 Census.

The Census Bureau calls April 1st Census Day. It’s when the bureau wants people to send back completed questionnaires. And so far Chicago’s got one of the lowest rates of return in the country.

Bruce Spencer is a Statistics Professor at Northwestern University. He says some people avoid filling out a form, and it’s not uncommon for households to be skipped completely.

SPENCER: If you have a garage for example, that has some living areas in it that wouldn’t be recognizable as such from the street that might not be classified as a housing unit. When the census bureau personnel walk around and try to make a list. If that’s the case, that wouldn’t get a questionnaire.

By Wednesday evening, the city was at a 38 percent rate of return, compared to the country’s rate of 52 percent.

During April through July, census takers are scheduled to visit households that do not turn in a questionnaire.