Let's take NYC for example. According to census data [1], Manhattan (a place many people definitely want to live) had a 10.5% vacancy rate last year. At almost 914,000 total housing units, that's almost 96,000 vacant homes.
According to the Bowery Mission [2], in the same time period there were 80,000 homeless people in NYC. So just in Manhattan, there were enough vacant homes for every homeless person in all five boroughs to get their own — with over 15,000 to spare!
[1] https://www.census.gov/library/visualizations/interactive/20... (change state to New York, click "Housing Unit Vacancy Rate" and then click Manhattan on the map)
[2] https://www.bowery.org/homelessness/
