Under rent control, landlords cannot afford to maintain a higher quality of housing. They also have no reason to maintain more attractive buildings in an environment of housing shortages resulting from rent control. Developers have no incentive to build in rent-controlled areas meaning that the existing housing gradually gets older and deteriorates. In San Francisco, three-quarters of the rent-controlled housing was more than half a century old, 44% were more than 70 years old. The unmaintained and decrepit buildings become uninhabitable. The artificial housing shortages then become all too real.