The landscape for affordable rental housing in the years leading up to the start of Window of Opportunity (WOO) was unsettled. There was widespread unaffordability of rental housing for low-income households as of 1990, which improved modestly over the course of the decade but not enough to make affordability widely within reach. Rents remained essentially flat through the decade while income rose, causing affordability to improve, but only somewhat. For example, the lowest income renters in 2000 would still have had to pay more than 30 percent of their income to rent a home at a corresponding percentile of rental prices in more than 90 percent of U.S. metropolitan areas.

Supply-side dynamics suggested troubling signs for preservation. An analysis of the evolution of the affordable rental housing stock from 1991 to 2001 shows that nearly one-third of affordable units in 1991 were no longer a part of the rental market in 2001 (compared with 6 percent of the 1991 supply where rents rose to become unaffordable by 2000), indicating that obsolescence was a larger threat than gentrification to the amount of affordable housing stock that remained affordable over the decade. All privately owned units with a HUD supply-side rental subsidy, including the project-based Section 8 program—one of the largest federal rental housing programs were either approaching or at the point where rent restrictions were expiring, introducing a new potential source for losses of affordable rental housing units. With this context in mind, in Chapter Three, we turn to the Window of Opportunity initiative. In Chapter Six, we analyze the broad trends in affordable rental housing in the years in which WOO operated.