After World War II, national homebuilding patterns changed decisively. Massive demand for housing existed after 16 years of depression and war. Postwar changes in housing finance and construction met that demand. Federal agencies guaranteed mortgages on 40 to 50 percent of all homes built in the 1950s. By 1970 half of all single-family home mortgages in the United States were federally underwritten. Builders flourished as down payments declined. They bought tracts of hundreds or thousands of acres and used new modular mass-production techniques to construct large residential subdivisions. One-quarter of the 60 million housing units of 1960 were built in the 1950s. Home owners surged from 40 to almost 70 percent of total households. America became a society where suburban home ownership was a key badge of “middle class” status.