Thousands of volunteers across the country spent a night in January canvassing their communities to look for people who may be experiencing homelessness, as part of the government's annual Point-in-Time count.
The count is required by the U.S. Department of Housing and Urban Development, and its results can be used alongside other factors to determine funding. But those estimates have often not been accurate, some experts told ABC News.
"We only have one day to get a snapshot of the homeless population," said Hannah Anderson with the YWCA, a Point-in-Time count organizer in Snohomish County, Washington. "You can't be accurate when you're counting people for one day."
An ABC News analysis found that methods and resources vary from community to community, producing an inconsistent, piecemeal account that even HUD acknowledges underestimates the number of unhoused people.
"The picture that HUD is getting, and that Congress is getting, and that the public is getting, isn't as clear as it could be and should be," said Eric Tars of the National Homelessness Law Center.
HUD Secretary Marcia Fudge told ABC News in an interview that the count is just a sampling of the country's homelessness crisis.
"It's not an exact science," she said, noting that if methodologies change from year to year, it could cause problems.
"There's no other way at this point for us to count all of the homeless people, so we just do a sample," she added.
Still, Fudge said HUD is considering ways to improve the process, noting that the agency does "believe that there are some better ways to do it."
On Monday, Fudge announced HUD's largest funding award of its kind: $3.1 billion to homeless services providers across the country that will fund more than 7,000 projects. The recipients entered HUD's funding competition last year with extensive applications that included their Point-in-Time count results, among other metrics.
Homelessness experts and institutions have been raising concerns about the Point-in-Time count for years.
Still, guidance surrounding the count has remained largely the same since it was first implemented in the mid-2000s. At least every other year, each community receiving HUD funding must conduct a Point-in-Time count in January, a time when people may crowd into homes with friends or family as much as possible to escape the cold.
"We wish that we could do [Point-in-Time] count when homelessness is at its highest, which tends to be early fall," said Maggie Thomas, a homeless services provider in Kansas City, Missouri. "But HUD says we do it in January, so we do it in January."
HUD Secretary Fudge told ABC News she doesn't know why the agency requires the count to be conducted in January, but that it will continue this practice for the time being.
"It doesn't seem like it makes a lot of sense, because it's cold, it's hard to find people, people are inside," Fudge said. "But that's what has always historically been done. And we just continue to do it the way it's always been done."
Aside from the timing, not much is standardized about the count: Organizations gather the data in different ways, with some more prone to undercounting than others, advocates for the homeless say.
"The data may not be consistent across jurisdictions, or even within a single jurisdiction from year to year," Tars said. "That makes it a little bit more challenging to draw meaningful data and trends from what's collected."
ABC News and the ABC Owned Television Stations' data team reached out to hundreds of Point-in-Time count organizers across the country to get a clearer picture of the scale of homelessness - and how they measure it - in their communities.