Prior to zoning revisions required by state planning laws adopted in 1973 (Comprehensive Land Use Planning Co-ordination Act, Oregon) and 1990 (Growth Management Act, Washington), residential zoning in the suburbs set large minimum sizes for new subdivisions. As late as 1978, the average minimum size for a new residential subdivision lot in the Metro urban growth boundary (outside the downtown Portland area) was 13 000 ft2 (Ketcham et al., A number of suburban cities in the region prohibited apartments. Instead of requiring a connected system of streets in new subdivisions, cities allowed developers to establish cul-de-sac communities that funnelled auto trips onto state highways. Residential development was haphazard and uncoordinated, led by private developers rather than by public investment.