U.S. Census Bureau director Robert Groves (seated) officially kicked off the 2010 Census by dogsledding to the first enumeration site in Noorvik, Alaska. Rural Alaskans are traditionally the first to be counted.

U.S. Census Bureau

In a country as large as the United States, how is it possible to count each person in every state, city, county, prison cell and hospital bed? Every 10 years, this is the daunting task assigned to the Commerce Department's Census Bureau. The census is mandated by the U.S. Constitution and goes all the way back to 1790, when less than 4 million people — not counting slaves or Native Americans — lived in the fledgling nation. In 2010, the census recorded 308.7 million people, a 9.7 percent population increase from 2000, or roughly 79 times as many residents as 1790 [source: U.S. Census Bureau].

The main purpose of the census is to figure out how many seats each state receives in the House of Representatives. Since 1911, there have been 435 seats in the House, and each state is guaranteed at least one [source: U.S. House of Representatives]. Additional seats are apportioned by population, with the most populous states receiving the most seats. California, the winner in this category, has 53 seats in the House, while states like Delaware, Alaska and South Dakota only have one [source: U.S. Census Bureau].

But the census is much more than just apportioning seats. It's a once-a-decade chance to track the shifting demographics of America. How many people live in big cities? How many children live in each household? What is the nation's racial and ethnic breakdown? Federal and state governments rely on census data to budget for social welfare programs and design public transportation systems. Cities and private industry use demographic figures to plan hospital expansions and housing developments, and assess the need for new schools or new strip malls.

Every year, federal and state governments use census data to allocate more than $400 billion toward public services and infrastructure [source: U.S. Census Bureau]. Because this data is so important, all U.S. residents (regardless of immigration status) are technically required by law to faithfully and accurately fill out the census form. When Minnesota Congresswoman Michele Bachmann announced that she would only answer the first question on the 2010 census form — and not provide individual names, ages or ethnicities of household members — she risked a fine of $100 to $500 for breaking the law. A census spokesperson confirmed the fines to Politifact, but added that they are rarely enforced [source: Farley].

So how did the census come into being?