SACRAMENTO — Participation in the 2020 census is lagging far behind a decade ago.

By the end of March, just under 38% of California households had responded to the decennial count of every person in the country, according to tracking data published by the U.S. Census Bureau.

That’s right in line with the national response rate so far. But at the same point 10 years ago, about 52% of California households had already mailed back their census forms.

Diana Crofts-Pelayo, spokeswoman for the California Census Office, said participation is trailing everywhere. The office crunched the Census Bureau’s tracking data from 2010 and found that, nearly three weeks after forms were mailed that year, the national response rate was 56%.

Officials are dealing with two enormous complications this year: The census moved online for the first time, so rather than being mailed the form, Americans are receiving reminders to fill it out on their computer or by phone. And the coronavirus outbreak disrupted the count just as it began, forcing the Census Bureau to suspend its field operations and community organizations to rethink their outreach campaigns.

“This is definitely something that no one was expecting to happen at this point,” Crofts-Pelayo said. “It’s really hard when you can’t have those person-to-person conversations.”

The stakes for states are enormous — the census will determine how many seats they hold in Congress and how much money they receive from the federal government.

California, which has large populations of non-English speakers, people in unstable living conditions and other hard-to-count groups, set aside $187 million for the count. That is more than six times what the state spent in 2000 and 2010 combined.

The Bay Area is doing better than most other regions of California. Three counties — Santa Clara, San Mateo and Contra Costa — lead the state with 44% or more participation. In San Francisco, 36% of households have filled out their census form.

But some of the rural corners of the state have seen response rates in the single digits — as low as 2% in Trinity County.

Because many of the residents in those areas do not have home mail delivery, the Census Bureau must drop off paper copies of the form. With field operations on hold until at least April 15, Crofts-Pelayo said, about 300,000 California households have yet to receive any census information.

The coronavirus pandemic has also delayed counts of the homeless population and group quarters such as college dorms, local jails and nursing homes. The deadline for the entire count was pushed back two weeks to Aug. 14, though census officials still plan to send out staff later this year to knock on the doors of those who did not fill out their form online.

Jeff Enos, deputy regional director for the U.S. Census Bureau in Los Angeles, said it was impossible to compare participation in the 2020 count to 2010, because it’s being done entirely differently.

“Currently, we’re pleased with the response rate. It’s within our projection,” he said.

But Jacqueline Martinez Garcel, CEO of the Latino Community Foundation, said it has been hard to cut through news about the coronavirus to draw people’s attention to the census.

Her organization has a contract with the state to oversee census outreach to Latinos. It garnered dozens of viewers Wednesday for a Facebook livestream to mark the official Census Day, far fewer than the thousands of attendees the group was expecting for a kickoff concert it originally planned. That event, along with hundreds of others across the state to help people fill out their forms, was canceled because of the pandemic.

“People are really preoccupied with some life-changing events,” Martinez Garcel said. “There’s no room to breathe or focus on anything else.”

Alexei Koseff is a San Francisco Chronicle staff writer. Email: alexei.koseff@sfchronicle.com Twitter: @akoseff