Want to help save the government money? Send in your Census.

For every one percent increase in the number of people who mail back their 2010 Census questionnaires, the U.S. government will save between $80 and $90 million.

That's because the U.S. Census Bureau is required to hire field workers to track down the estimated 130 million people who don't return their questionnaires.

If that's not enough reason to turn in your Census forms, consider that they help ensure that your state gets its share of federal money and federal representation.

Census data is used to determine how many representatives a state gets in the House, as well as how many votes it gets for president in the Electoral College. (It does not affect the number of senators.)

The 2010 Census process began last spring when bureau field workers went door-to-door with GPS computers in order to verify every address in the United States.

Field workers were looking for all types of homes, even the ones that might exist in hard-to-find places, such as renovated industrial buildings in New York City or rehabbed barns in rural Iowa.

In March, the Census Bureau will begin the second phase of the 2010 Census, when it sends out a 10-question form to each address.

The questions will include things like how many people live in your household, and what is your telephone number.

Field workers will do follow-ups between April and July, and in December of next year, the Census Bureau will send the population information to the president, as mandated by law.

In most situations, giving a total stranger your phone number or address would be a bad idea, so it is important to verify that the person at your door actually works for the Census.

"We make it clear that if somebody feels uncomfortable they should take precautions," said Eun Kim, a Census Bureau spokeswoman. "Each representative will provide the resident with supervisory contact information and a regional office phone number for verification."

Additionally, the field worker will usually be carrying some kind of bag or gear that has the Census Bureau written on it, Kim said.

Here are a few other things you should know about the upcoming Census:

* If you mail back your 2010 forms successfully and completely, no one from the bureau will come to your home.

* If you have not returned your form or have not answered each question completely, a field worker from the Census Bureau will only knock on your door between April and July 2010.

* If a field worker does knock on your door you can ask him or her to share with you the following: a valid identification badge, contact information of a supervisor or regional office and a letter on official Census Bureau letterhead.

* A bureau representative will never ask you for your Social Security number, bank account number, or a credit card number.

* The Census Bureau will never contact you by e-mail.

Leah Carliner writes for Congressional Quarterly.