How many House/Condo owners are there in the US? What is the source?

Answer 1

One way to know would be contact all the property tax agencies and add up the totals. Lot of work, don't know if anyone has ever done it. ( just counting mortgages won't do because lots of people own outright ) ( the IRS wouldn't work because many people who own outright don't have enough deductions to itemize, so the property taxes don't show )