Every 10 years, we have to count people. At least that's what Article 1, Section 2 of the Constitution says. It doesn't sound too complicated. But it is. Who gets counted, and how, determines not only congressional representation but how funding is distributed for a slew of federal programs that affect all of us. As we prepare to stand and be counted in 2010 -- and the U.S. Census Bureau is spending a lot of advertising money to make sure that everyone is -- let's note a few misconceptions about our population and the efforts to tally us up.

1. Immigration is the biggest force behind the nation's racial and ethnic diversity.

If immigration stopped today, we would still see substantial gains in our minority populations for decades to come. Recent Census Bureau projections showed that under a "no further immigration" scenario, the minority share of our population would rise from about 35 percent today to 42 percent in 2050. The preschool (under age 5 ) population would become minority white. The greater minority presence would arise from higher natural-increase rates for minorities than for the aging white population. This momentum is already in place: Since 2000, natural population increase accounted for 62 percent of the growth of Hispanics, the country's largest minority group, with immigration responsible for the rest.

Already, the District and four states (Hawaii, New Mexico, California and Texas) are minority white, and in six more, whites are less than 60 percent of the population. Minorities now make up more than 30 percent of the residents in half of the nation's congressional districts, compared with a quarter in 1992.

The census will tell us more about the dispersal of Hispanics and other groups to traditional white enclaves -- suburbs and the country's midsection. A majority of all Hispanic, black and Asian residents of major metro areas now live in the suburbs. And since 2000, according to recent estimates, the fastest Hispanic growth occurred in South Carolina, South Dakota, Tennessee and Arkansas.

Color lines within our population are blurring in a different way, too, with people who identify with more than one race. The number of mixed-race married couples more than doubled since 1990, and they make up nearly 8 percent of all marriages.

2. The country is getting uniformly older.

As a baby boomer, I am part of a demographic mob. As we age over the next 20 years, the nation as a whole will see a surge in senior citizens. But different parts of the country will be aging at different rates, largely because selective "younging" is going on. This is evident from census estimates showing that during the first nine years of this decade, 25 states -- mostly in the Northeast, Midwest and Great Plains -- and the District exhibited absolute declines in their child populations, while 25 others, led by Nevada and Arizona, showed gains.

This variation in where families and children live is poised to shape a young-old regional divide that could intensify over time. Census projections for 2020, made earlier this decade, showed median ages over 40 in Maine, West Virginia and Pennsylvania, compared with below 36 in Utah, Texas, Georgia and California.

3. Big states will keep getting bigger -- especially in Congress.

For much of the postwar period, the Sunbelt megastates of California, Florida and Texas just kept growing: They led all other states in adding congressional seats based on censuses since World War II. But the economic turbulence of this past decade will affect their political fortunes. Florida was one of the nation's growth leaders for the first half of the decade and was poised to gain as many as three congressional seats after the 2010 Census, tying or overtaking New York's congressional delegation. But the mortgage meltdown led to an unprecedented exodus from the state in the past two years. Florida's likely gain of one seat will be its smallest addition since the 1940 Census.

California is not positioned to gain any seats for the first time since statehood in 1850. Despite its status as an immigration magnet, the Golden State lost large numbers of people fleeing high housing costs during the bubble years. California might have even lost a seat had that bubble not burst.

Of the three Sunbelt behemoths, Texas will take the biggest prize, probably four congressional seats -- its largest increase since the 1880 Census. It was largely immune from the housing crisis late in the decade, while it gained Katrina-driven migrants from Louisiana.

4. The census is the main source of information about our population.

Not as much as before. Unlike previous censuses, the 2010 count will provide only bare-bones information that does little more than fulfill its constitutional mandate. The questions will include the age, sex, race, Hispanic origin and household relationship status of each individual, and the size and homeownership status of each household.

What happened to all the rich data on poverty, income, ancestry, immigration, marital status and some 30 other categories we have come to expect from the census? Those "long form" questions have been given to a sample of census respondents in every count going back to 1940 -- but they won't be handed out this year. The queries have been diverted to the Census Bureau's American Community Survey.

In 2005, the bureau began administering the ACS to 3 million households each year to elicit the same kind of information that was previously available only every 10 years. This large and sophisticated survey has already provided important and timely insights on changing poverty, immigration and migration patterns in this economic roller coaster of a decade.

5. New technology gives us much more demographic data than the census can.

Not true. Technological developments and data collected via the Internet do give us new ways of looking at the population, and complex surveys and estimates conducted by the Census Bureau and other organizations allow us to monitor change over the decade -- but there is no substitute for counting everyone. Aside from the census's constitutional mandate to provide the basis for congressional apportionment, a national headcount also allows us to know how many people live in the nation's cities, suburbs and neighborhoods and to break them down according to race, age and gender.

There are plenty of examples of a decennial census surprising the experts. The 2000 Census, for instance, discovered sharp population surges in many old, large cities. This was unanticipated for Chicago, which had experienced decades of decline. And the spread of the nation's Hispanic population into new states such as North Carolina far exceeded expectations.

Many government and private surveys, including the ACS, rely on the decennial census to make sure their work accurately reflects the population as a whole.

This census will also tell us more about small but growing groups, such as same-sex married partners and multiracial populations, whose presence and interests can change laws and public policies.

The Census Bureau's ad campaign urges Americans to answer "10 Questions in 10 Minutes" -- and those are still 10 very important questions, whose responses will guide us for the next 10 years.

If you're an upstanding U.S. citizen, you'll stand up and be counted this Election Day, right? Well, maybe not. Just because Americans can vote doesn't mean they do. But who shows up is what decides the tight races, which makes turnout one of the most closely watched aspects of every election -- and one that has fostered a number of myths. Here are five, debunked:

1. Thanks to increasing voter apathy, turnout keeps dwindling.

This is the mother of all turnout myths. There may be plenty of apathetic voters out there, but the idea that ever fewer Americans are showing up at the polls should be put to rest. What's really happening is that the number of people not eligible to vote is rising -- making it seem as though turnout is dropping.

Those who bemoan a decline in American civic society point to the drop in turnout from 55.2 percent in 1972, when 18-year-olds were granted the right to vote, to the low point of 48.9 percent in 1996. But that's looking at the total voting-age population, which includes lots of people who aren't eligible to vote -- namely, noncitizens and convicted felons. These ineligible populations have increased dramatically over the past three decades, from about 2 percent of the voting-age population in 1972 to 10 percent today.

When you take them out of the equation, the post-1972 "decline" vanishes. Turnout rates among those eligible to vote have averaged 55.3 percent in presidential elections and 39.4 percent in midterm elections for the past three decades. There has been variation, of course, with turnout as low as 51.7 percent in 1996 and rebounding to 60.3 percent by 2004. Turnout in the most recent election, in fact, is on a par with the low-60 percent turnout rates of the 1950s and '60s.

2. Other countries' higher turnout indicates more vibrant democracies.

You can't compare apples and oranges. Voting rules differ from nation to nation, producing different turnout rates. Some countries have mandatory voting. If Americans were fined $100 for playing voter hooky on Election Day, U.S. participation might increase dramatically. But in fact, many people with a ballot pointed at their head simply cast a blank one or a nonsense vote for Mickey Mouse.

Moreover, most countries have national elections maybe once every five years; the United States has presidential or congressional elections every two years. Frequent elections may lead to voter fatigue. New European Union elections, for instance, seem to be depressing turnout in member countries. After decades of trailing turnout in the United Kingdom, U.S. turnout in 2004 was on a par with recent British elections, in which turnout was 59.4 percent in 2001 and 61.4 percent in 2005.

Americans are asked to vote more often -- in national, state, local and primary contests -- than the citizens of any other country. They can be forgiven for missing one or two elections, can't they? Even then, over the course of several elections, Americans have more chances to participate and their turnout may be higher than that in countries where people vote only once every five years.

3. Negative ads turn off voters and reduce turnout.

Don't be so sure. The case on this one is still open. Negative TV advertising increased in the mid-1980s, but turnout hasn't gone down correspondingly. The negative Swift boat campaign against Sen. John F. Kerry (D-Mass.) apparently did little to depress turnout in the 2004 presidential race.

Some academic studies have found that negative advertising increases turnout. And that's not so surprising: A particularly nasty ad grabs people's attention and gets them talking. People participate when they're interested. A recent GOP attack ad on Rep. Harold E. Ford Jr. (D-Tenn.), a Senate candidate, has changed the dynamic of the race, probably not because it changed minds or dissuaded Democrats, but because it energized listless Republicans.

We'll have to wait to see whether the attack on Ford backfires because voters perceive it as unfair. That's the danger of going negative. So campaigns tend to stick to "contrast ads," in which candidates contrast their records with those of their opponents. When people see stark differences between candidates, they're more likely to vote.

4. The Republican "72-hour campaign" will win the election.

Not necessarily. You can lead citizens to the ballot, but you can't make them vote.

Republicans supposedly have a super-sophisticated last-minute get-out-the-vote effort that identifies voters who'll be pivotal in electing their candidates. Studies of a campaign's personal contact with voters through phone calls, door-to-door solicitation and the like find that it does have some positive effect on turnout. But people vote for many reasons other than meeting a campaign worker, such as the issues, the closeness of the election and the candidates' likeability. Further, these studies focus on get-out-the-vote drives in low-turnout elections, when contacts from other campaigns and outside groups are minimal. We don't know what the effects of mobilization drives are in highly competitive races in which people are bombarded by media stories, television ads and direct mail.

Republican get-out-the-vote efforts could make a difference in close elections if Democrats simply sat on the sidelines. But this year Democrats have vowed to match the GOP mobilization voter for voter. So it'll take more than just knowing whether a prospective voter owns a Volvo or a BMW for Republicans to eke out victory in a competitive race.

5. Making voter registration easier would dramatically increase turnout.

Well, yes and no.

In 1993, the Democratic government in Washington enacted "Motor Voter," a program that allowed people to register to vote when they received their driver's license or visited a welfare office. Democrats thought that if everyone were registered, turnout rates would increase -- by as much as 7 percentage points.

But while many people registered to vote, turnout didn't go up much. Subsequent studies found only small increases in turnout attributable to Motor Voter, perhaps 2 percentage points.

Sizable increases in turnout can be seen in states with Election Day registration, which allows people to register when they vote. This may be related to the fact that lots of people don't make up their minds to vote until Election Day, rather than months in advance when they get a license.