Census worker Anna Arroyo takes calls about the census at City Hall in Reading, Pennsylvania, on September 1.

This is what could happen if the 2020 census fails to count everyone in the US

Updated 9:30 AM ET, Mon September 14, 2020

(CNN)If the 2020 census fails to count everyone in the US, experts warn that the consequences will be serious, widespread and long-lasting.

The census is the basis for determining how many representatives each state gets in Congress and how an estimated 1.5 trillion dollars in federal funding are spent. It only happens once every 10 years.
And time is running out to get it right.
So if you haven't had a chance to follow what's going on with the 2020 count, now is the time to take notice -- because no matter where you live in the US, many important things in your community are at stake.
Three ways to participate in the 2020 census

Census workers are currently visiting homes that haven't responded to the 2020 census. US households that haven't responded to the census can still do so by:

• Responding online at 2020census.gov

• Responding by phone at 844-330-2020

• Completing and mailing back paper questionnaires

More information is available on the US Census Bureau website.

"The census, when you boil it down, is about two things: It's about power and it's about money," says Jeff Robbins, a census administrator for the city of Mesa, Arizona.
And one thing, Robbins says, is keeping him awake at night: "What happens when we run out of time, and not everybody's counted?"
Currently, the count is scheduled to end September 30. Legal battles are raging over a series of last-minute changes to the census. And groups across the country are scrambling to boost response rates before it's too late.
Some Los Angeles restaurants recently distributed free meal vouchers in an effort to boost census response rates.
Census officials maintain they're committed to producing a complete and accurate count. And a top official for the agency said in a recent court declaration that the bureau is on track to do so.
But demographics experts, local officials and advocacy groups have a lot of concerns that this year's tally won't be accurate, because a pandemic and politics got in the way. They're raising alarm bells that a significant undercount is likely.
If that happens, here are some of the key things at risk:

States could lose representatives in Congress

The 2020 census could have a big impact on the balance of political power. Census data is used to determine how many seats states get in Congress, and to draw redistricting maps.
The population numbers from the 2020 census could play a big role in shaping the balance of power in Washington. The data is used to redraw congressional district boundaries. And through a process known as apportionment, the data will be used to determine how many representatives each state gets in Congress. Some states could lose seats if there's an undercount.
Martha Maffei says that's something she's worried could happen again in her state -- New York -- which already lost two seats after the 2010 census. As the executive director of SEPA Mujer, an immigrant advocacy group in Long Island, she's been pushing for more people to participate in the 2020 count. But she says widespread fear in the community has made it tough, and the Census Bureau's recent decision to end the count a month early made it even tougher.
"It's going against our efforts. It just makes it very hard. I think all our elected officials, our representatives, congressmen, everybody should be doing something to reverse that decision, because we are going to be hurt very badly," she says.
It's possible the deadline could change; that's the subject of a legal battle playing out in a California federal court.
Several lawsuits are also pending over the Trump administration's recent announcement that it plans to exclude undocumented immigrants from any census figures used to determine the number of representatives states get in Congress. On Thursday, a panel of federal judges in New York blocked that directive, ruling that Trump's July memorandum on the census violated federal laws. If the Justice Department appeals that ruling, the Supreme Court could have the final say.

Children might miss out on needed funding for schools and other programs

Even before a pandemic upended plans for the 2020 count, experts were worried a lot of children would be missed in this year's census. Undercounts of young children -- and particularly Latino and African American children -- have been a perennial problem. Now, those fears are even more acute.
"We are very concerned," says Dr. Sally Goza, president of the American Academy of Pediatrics.
The 10 largest federal programs serving children distribute $160 billion every year using data from the census, Goza says.
And we've seen before what happens when children aren't counted. More than 2 million young children were missed in the 2010 census count because of a range of errors that census officials have been analyzing for years.
"That cost more than a billion a year in funding for programs because they weren't counted," Goza says. "That's a lot of lost money that could help our children, and we just don't want to see that lost again."
Experts are worried the 2020 census could undercount children, leading to funding shortages for important programs kids need.
Programs that support children's healthcare, food and education would be impacted, she says. Among them: The National School Lunch Program, Head Start and the State Children's Health Insurance Program.
"This is critical," Goza says. "This is a once-in-a-decade opportunity. It's going to affect us for the next 10 years. The negative ramifications really affect our children."
Robbins, the Arizona official, suggests thinking of it another way.
"If you think of kids that are in the fourth grade, they're going to be basically out of the school system by the time you've got another shot at this," he says. "This affects generations."

Communities of color could end up getting less funding for health care