The weather is getting warmer, the days longer. The Phillies’ home opener Thursday marked the start of the baseball season. The region will host hundreds of festivals and community events on breezy spring afternoons and sunny summer mornings.

And the U.S. Census Bureau plans to take advantage of it all.

Counting every person residing in the United States during the 2020 census is a massive undertaking. And to do it, the bureau has started an extensive nationwide recruiting effort, planning to hire 400,000 to 450,000 census takers — 10 times the capacity of Citizens Bank Park — to knock on doors to follow up with their neighbors who do not fill out their census forms.

That’s in addition to scores of supervisors, managers, and administrative workers.

As with every census count, the bureau plans to recruit at events and at community centers, houses of worship, and any other place where people gather.

One potential roadblock the bureau faces this year that it didn’t in 2010: the country’s low unemployment rate. In 2010, just after the end of the Great Recession, it was near 10 percent. Now, the national unemployment rate is 4 percent.

“That’s a concern for us,” said Jane Konstanty, assistant regional census manager for the Philadelphia area. “It’s a challenge.”

Population counts taken in the census every 10 years determine the allocation of hundreds of billions in federal funds to state and local governments, the boundaries of voting districts, and the number of seats each state gets in the U.S. House. Philadelphia alone receives more than $3 billion in federal funds each year based on census counts.

Four 2020 Census offices opening in the region this summer or fall — two in Center City, one in Norristown, and one in Wilmington — will hire a total of about 2,500 census takers to work in the field.

The bureau is marketing the temporary positions as opportunities for people to supplement their incomes and to help ensure their communities get the money the federal government owes them. Census officials say residents are more likely to respond to census questions asked by someone from their own neighborhoods.

“We have a lot of need for people from the community, that are involved in community activities, and know the community, and care about their communities,” said Fernando Armstrong, director of the Census Bureau’s Philadelphia Regional Office.

The jobs typically will last several weeks and include day, evening, and weekend shifts. Workers will share their availability and receive assignments.

Pay varies by location. Census takers will make $21 an hour in Philadelphia and $16.50 in Camden County. The Census Bureau also compensates field workers for travel.

Applicants for 2020 census positions must be U.S. citizens at least 18 years old, and have a Social Security number and an email address. The bureau also conducts criminal background checks to rule out applicants such as those convicted of violent crimes.

To apply, go to 2020census.gov/jobs or to usajobs.gov for management positions.