I am no bull, but occasionally I see one or two things they do. (usually just not to the same extent). Now I can be totally wrong, but didnt tax law change in 1997 to allow the deduction of up 500k in housing profits? (250k individual). Taxes on 500k is alot of money, something that would then be plowed into the value of the house.

Also the trend line pre WWII is nice to see, but not as usable as the trend line afterwards because lifestyle is differnet now. The boom in the late 1940’s is due to the rise of suburbia by returning WWII verterans and their starting families. Also, WWII started women in the work force, and while it took 20 years to bloom, the beginnings of it can be traced to lower middle income people deploying the female in the relationship to get a job to raise the standard of living. Nurses, teachers, secretaries, these were all acceptable jobs for women in the 1950’s that were often male dominated previously. Also previous to 1940 most people lived in cities or on rural farms and a car was an unusual thing. People either lived on the land they worked or near the factory/building.
The rise in 1970 can be attributed to the baby boom generation. The first boomers were born in 1946 and take that out to 23-24 years later (marrage and college age) and there is your spike. Demand from one of the largest generations hit the market. The boom in 1997 can be linked to a change in tax rates and demand from the baby boom generations children (1997-1970= 27years old).

None of this explains the giant spike observed between 2000 and 2007. That was loose lending and ignoring risk in lending markets. That will self correct. No generational or immigation shift I know of can explain the 2003-2005 insanity.