If you're the head of an American household, the odds are a little better than even that you've already mailed back your census form. However, around 48 percent of households are dragging their feet, so let's take a look at a few questions you might have about everyone's favorite once-a-decade survey.

Why do we need a census, anyway?

Aside from the obvious necessity of knowing how many people there are in the country and how best to allocate our resources among them, the Constitution demands an enumeration of the population every 10 years. Article 1, Section 2 of the Constitution states that the first enumeration of the population would be made within three years of the ratification of the Constitution and every 10 years after that. The first census in 1790 found that 3,929,326 people resided in the United States, including nearly 700,000 slaves.

How much cash is at stake here?

According the Census Bureau, census responses help allocate over $400 billion in federal spending each year. For comparison, that figure is larger than the entire gross domestic product of Switzerland and the United Arab Emirates.

Counting everyone in the country can't be cheap. What sort of budget does the Census Bureau have?

The tab for the census is pretty steep. This year's census has a budget of $14.7 billion! At its peak, the Census Bureau will be employing over 1.4 million people in an effort to get the job done.

Want to help keep government expenditures down? Mail back your form. According to Census Bureau Director Robert Groves, every one percent increase in response rate saves the government $85 million in salary and other costs associated with sending workers door-to-door to track down non-responders.

These potential savings explain why you kept getting mailings about the census well before the actual form ever landed in your mailbox; the Census Bureau estimated that by spending around $80 million on advance mailings and advertisments, it could bump the response rate by 6 to 12 percent.

What happens if I don't fill out my census? Am I going to jail?

No, you probably won't be making a trip to the stony lonesome if you scoff at filling out your census. According to Title 13 of the United States Code, anyone who refuses or willfully neglects to fill out his or her census can be slapped with a fine of not more than $100.

You're probably only going to get a fairly small fine if you adamantly refuse to fill out your census. However, the Census Bureau will pester the heck out of you before it ever gets that far. If you didn't mail back the census form you already received in the mail, you'll be receiving a replacement to give you a second chance. If you still refuse to answer, a Census Bureau worker will show up at your door to ask you the questions. If you're not home, they'll leave a door hanger and come back. These guys are persistent.

Can I just lie?

Because the Census Bureau cannot legally share your responses with any other government office, including the IRS, the FBI, and any other security agency, there's not much need to tell any fibs. If you do, however, there's a fine of up to $500 for knowingly providing false answers.

Has the census always been so confidential?

Unfortunately not. During World War II, the Second War Powers Act of 1941 ended the legal confidentiality of census records. The FBI and other government agencies were then able to use census information to track down Japanese nationals and Americans of Japanese descent in their efforts to intern the Japanese population. The confidentiality of the census returned in 1947, and since then it's been impossible for other government agencies to get at residents' responses.

How do we count the homeless?

Since the Census data is collected on a home-by-home basis, it's tricky to count people who don't have homes. However, the Census Bureau says it counts homeless people by tracking them down at service and outreach locations where displaced folks often congregate, like soup kitchens and shelters.

Have past censuses had any weird questions?

The first census looked somewhat like the one that you filled out this spring with the exception of questions aimed at counting slaves. Although the Constitution only requires that the census get an accurate count of Americans, the survey eventually expanded to look at topics like race, employment status, and home ownership. Some censuses have had stranger questions that seem a bit insensitive or outdated today. Take a look at some of these:

"¢ The 1830 version asked for households to count how many "deaf and dumb" residents of various ages lived in the home.

"¢ The 1840 census inquired about the number of blind residents and the number of "insane and idiotic in public or private charge."

"¢ The 1850 census kept those questions and also asked whether a resident was a "pauper or convict." Additionally, it asked whether or not slaves are "fugitives from the state."

"¢ In 1890 the census asked if residents were "defective in mind, sight, hearing or speech, or whether crippled, maimed or deformed, with name of defect" and "suffering from acute or chronic disease, with name of disease and length of time afflicted."

"¢ The 1930 census asked if the respondent owned a radio set or a farm.

As a country, how are we doing on mailing in our forms?

In a move that either shows the Census Bureau has a sense of humor or is somewhat oblivious, April 1, 2010 was Census Day. As of April Fools' Day, the national response rate was 52 percent. Among areas with more than 50,000 people, Dubuque, IA; Green, OH; and Livonia, MI are leading the way with 73 percent response rates.

What if I haven't sent back my form yet?

On April 10, the Census Bureau is going to start sending out volunteers to encourage laggards to mail in their forms. Once the Census Bureau sees how successful that effort is, it will know how many in-person census takers it has to hire to send after non-responders.

When can sociologists, economists, and other scholars get their mitts on the data?

If they're just looking for the aggregate data, scholars can take a peek at it as soon as it rolls in. If they want individual data, though, the wait is quite a bit longer. Data regarding individual responses isn't available to the public until 72 years after the census in question was taken.

I thought the census was supposed to be a hassle. Why was the form so short?

In years past, most households received a fairly brief census form that only asked a dozen or so questions. A certain percentage of households, though, got the "long form," which asked for all sorts of detailed economic data.

For this census, the Census Bureau did away with the long form. Instead, they'll get their detailed economic information through the annual American Community Survey that will be sent to a smaller sample of around 3 million households. Using an annual survey instead of a once-a-decade census will give the government a more accurate snapshot of what's going on in the economy at any given time.

When do we get the results?

By law, the Census Bureau has nine months to deliver its results. Since April 1 was Census Day, the results have to be ready by December 31, 2010. That means demographers are going to have some crazy New Year's Eve parties.