Coronavirus presents challenges for census.

How do you count people in an era of social distancing?

As the U.S. Census Bureau kicks off its once-a-decade effort to count every single person in the country, organizers and officials face a new but not entirely unexpected challenge: coronavirus.

And the Bay Area, with a growing number of people testing positive for COVID-19, offers a case study in the questions now popping up: How can we educate residents about the census amid canceled events and social distancing? How can we count college students on campus when they are scattering as universities turn to online classes? And what about plans to count homeless residents if an outbreak shuts down services or makes encampments dangerous to enter?

“The options for modifying census operations in light of the coronavirus might include extending the end of the doorknocking phase in order to count all households that haven’t responded on their own,” said Terri Ann Lowenthal, a former staff director of the House census oversight subcommittee.

The bureau, which is supposed to end door knocking in July, might also consider expanding its use of data that other government agencies already collect to fill out missing numbers, Lowenthal said.

An inaccurate count could be devastating — the numbers collected in the next few months are used to determine congressional and state representation, distribute $1.5 trillion in federal funds, even guide where businesses open and what they sell.

In a statement posted on its website Wednesday, the Census Bureau said it was committed to completing the count on schedule and encouraged people to respond online. Although it said that it was creating a task force to monitor the situation and that contingencies have long been in place for pandemics, the bureau did not indicate any substantial changes to its operations.

“If we need to delay or discontinue nonresponse follow-up visits in a particular community, we will adapt our operation to ensure we get a complete and accurate count,” the statement said.

On Thursday, households started receiving the first of several letters explaining where to fill out questionnaires. For the first time, people will be able to