Longtime readers know I've been addressing housing issues from the start of the blog in 2005. Let's start with the general context of housing in the US, courtesy of the US Census Bureau, which tracks occupancy and the number of housing units nationally: Quarterly Residential Vacancies and Homeownership, 4th Quarter 2023

All housing units 145,967,000

Occupied 131,206,000 Owner 86,220,000 59%
Renter 44,985,000 31%

Vacant 14,761,000 10%

Non-seasonal (i.e. not second homes owned by the wealthy for their recreational use) 11,177,000

Units vacant because they're in the process of being rented or sold:
For rent 3,224,000
For sale only 757,000
Rented or Sold 783,000

Held off Market (occasional use, temporarily occupied, other) 6,414,000

Seasonal (i.e. second homes owned by the wealthy for their recreational use) 3,583,000

TOTAL Held off Market and Seasonal / Recreational: 9,997,000

In summary: there are 14.7 million vacant dwellings in the US, of which 10 million are not available for year-round rentals or sale. Those 10 million dwellings are comparable to the total number of dwellings in entire nations, for example, Australia (11 million housing units, population of 27 million).