Concerns about the supply of rental housing affordable to lower-income households have become especially acute during the past decade, as stagnant wages for many Americans coupled with a recession have increased demand for affordable rental units even as factors like gentrification, loss of units through deterioration, and loss of subsidies have decreased supply. Though new construction is one response to this mismatch, it has not kept up with demand—or even with the loss in existing affordable-housing stock. This disparity alone illustrates the importance of preserving current affordable housing. Preservation also carries with it a number of benefits: it’s generally less expensive than new construction (about one-half to two-thirds as much), it lets people stay in their homes, and it is already integrated into land-use patterns (HUD 2013).