The coronavirus pandemic couldn't have arrived at a worse time for the 2020 census. The once-in-a-decade count was just about to kick into overdrive when the crisis upended American life.

Rallies, doorknocking and other events encouraging people to fill out their forms around Census Day, April 1, have been canceled. Plans to contact hard-to-count college students, homeless people and remote rural residents have been delayed, as have training sessions for census takers and other operations.

Most households across the state have recently received letters directing them to fill out the census online — a new option for 2020. More than 29% of households had done so as of Tuesday.

The complex work of hunting down people who haven't responded is now slated to begin in late May, when thousands of people who signed up to work for the census will be dispatched to doorsteps across the state.

That could be a tall order, however, if virus-related restrictions remain in place after a delayed start.

"I think it's going to make an already challenging census more challenging," said Andrew Virden, the state's director of census operations. "This will stress the importance of people taking advantage of the self-response period [to fill out the form] before the end of April so that a stranger doesn't come to their door."

Virden said they hope to replace planned doorknocking efforts with phone banking. The state had also set up more than 400 question assistance centers for people seeking help, but more than 200 of them are libraries — which may no longer be open.

"This was not anything any of us could have anticipated or planned," Al Fontenot, the bureau's associate director of decennial census programs, told reporters Friday. "Of all of our worst nightmares of things that could have gone wrong with the census, we did not anticipate this set of actions."

More than two centuries since the country's first census, there is no precedent for a crisis of this magnitude coinciding with the decennial count, said census historian Margo Anderson.

"They're really in uncharted territory," Anderson said. The 1918 influenza pandemic, by contrast, took hold long before the 1920 census rolled around.

"Right smack dab in the middle of the two months when we should actually be counting, we have a national crisis," Anderson said. "And one that basically restricts people."

The virus will also complicate counting the homeless, who are typically counted wherever they are located on April 1 ­— though counting will now begin later. Hennepin County has begun moving homeless seniors to suburban hotels, meaning they may be counted in Bloomington rather than where they typically reside in Minneapolis.

Monica Nilsson, who operates two homeless shelters in Minneapolis, said that could mean the city loses out on more than $5 million over the next decade, based on estimates that each person counted garners $2,800 in federal funding for their community.

"Minneapolis deserves that income because they are the ones who care for the homeless community," said Nilsson, who is advising Hennepin County on counting the homeless.

The Census Bureau is also encouraging homeless shelters to provide information on their residents so census takers don't need to conduct in-person interviews. But Nilsson said shelters are already experiencing staff shortages and dealing with complex quarantine arrangements.

"We are scrambling as it is in our shelters," Nilsson said.

"We all depend on the census helping us get proper data," she added. "It's just not the time for this right now."

Alberder Gillespie, Minneapolis census coordinator, said more than a dozen events aimed at raising awareness about the census have been scuttled, including a doorknocking in north Minneapolis and a powwow on Franklin Avenue.

Gillespie said the 2020 census was already unique in many ways because of the fight over the citizenship question and community fears about deportation.

"Now we have COVID-19. So it's been a roller-coaster ride, to say the least," Gillespie said.

But technology may make things easier.

"I think if we didn't have the census available online this cycle, or via telephone, we'd be in a much worse position," Gillespie said.

Counting college students will also be challenging, because many have now left campus for the semester after the virus forced classes to move online.

Normally census takers would scour the University of Minnesota neighborhoods beginning in April to ensure that students in off-campus housing fill out their forms. That operation was delayed two weeks. But with many students back at home, the university is trying to encourage them through e-mail, social media and other means to respond to the census with their normal address at school.

"Even in a good year when everything goes great, we're concerned about undercounts," said Mike Miller, who co-chairs the university's Census Complete Count Committee. "This is another challenge that makes that more of a reality."

Alex Beck signed up to be an enumerator and was told training would begin in late March. But last week he received an e-mail saying the training has been pushed back to April 15, at the earliest.

"I don't really know when it's going to start at this point," Beck said.