Mick Ireland knows Pitkin County’s streets. The former Aspen mayor and 30-year politico has knocked on thousands of his neighbors’ doors over the years, promoting candidates and ballot issues as well as helping to register voters.

So when the 2020 census report showed entire blocks in Pitkin County — not city blocks but the small geographic areas that the U.S. Census Bureau breaks the country into — with populations of zero, he took note. Using the county’s geographic information system – GIS – mapping, he started finding more blocks across the county that appear to have been missed by the 2020 census. In some blocks the census counted fewer homes despite new construction.

“I know those buildings simply didn’t disappear. My estimate is that about 1,000 people were not counted,” said Ireland, who is working with county leaders to assemble a detailed list that could become a formal challenge to the 2020 census count.

More counties are doing the same. After census takers struggled to count every U.S. resident in their place during the chaotic pandemic, more counties in Colorado are finding discrepancies with the tally that will determine how many federal dollars flow into communities. (The 2010 census showed that 316 federal spending programs relied on the 2010 count to distribute about $1.5 trillion in annual spending. Colorado gets about $19.2 billion a year in census-guided funds, which amounts to about $3,500 per resident.)

So a count that comes up 1,000 short in Pitkin County, could cost the county $35 million over the next decade.

Read the full story via The Colorado Sun.