I was a real estate appraiser in the 1980s. Residential property values in Texas dropped around 40% from 1984ish to 1989ish. Commercial valuations dropped even more, probably 50+%.
It was a brutal time. In Houston, several large subdivisions had every single home foreclosed on. People paid $100-120,000 for them new with all sorts of points, closing costs, etc.. included and minimal down payments. Values went down to $60000+/- if in great shape, $40,000 if trashed. Entire neighborhoods just walked away. Our office did numerous condominium projects where every unit had been foreclosed on. We did most of the Galveston condominiums that were financed by Gibraltar. Every vacation unit owner walked away.
In Austin, we did 1000s of NPC, Milburn, etc... tract home builders that had minimal down payments and lots of financing costs built in.
In San Antonio, we did 1000s of Ray Ellison foreclosures. Probably the largest declines overall. His incredibly cheap quality builds deteriorated quickly and he built the most financing, furniture, pools, etc... into the price. Very sad for a lot of families. To pay $125,000 new and 4 years later be worth $50-60,000.
The change of the tax code destroyed the commercial market. Overnight, apartment projects were worth less than 1/2 of what they were. Cap rates? 20-30% after the change in tax code and lack of financing. Units traded less than $10,000/door. It became impossible to sell a strip center. No tenants and no financing. Lenders were giving them away. Fourplexes in Austin were renting for $500/unit and lenders could not sell them for $40,000. Class A buildings were owned by the lenders and they became landlords since they could not sell them. Vacancy rates were over 50% and rents were $0.50 to $1.50/ft.