In addition to redistricting, the government uses census data to provide more than $185 billion in services every year, in programs ranging from schools, hospitals and infrastructure to senior services and daycare.

Private industry also takes advantage of census data. Corporations use the demographic information the census provides to evaluate regional growth.

"Census data [is] the informational bedrock for industry and market research and investment planning," Clinkenbeard says. "[When companies are deciding] where to put that shopping mall or McDonald's, some of the data they look for is the census."

The census office releases information in statistical form only. All personal responses remain confidential for 72 years.

Playing the Numbers Game

The federal government has allocated $6.8 billion to fund the census effort.

Twelve regional offices and 520 local offices have been established to help in its administration. The Boston regional office, located at Copley Place, serves all of New England and upstate New York, and the local census office, located in East Cambridge, targets Cambridge, Somerville, Melrose, Malden and Medford.

This year the government has embarked on a much more aggressive advertising campaign to inform the public about the census and to encourage responses.