As more people are becoming renters — outnumbering homeowners in some areas — many cities lack registries to keep track of the number of rental properties and who owns them. The strongest rental registries are built to solve a clear problem,” said Chano Murray. Issues might include identifying absentee or corporate landlords, supporting rental assistance programs, understanding local rent conditions, or improving enforcement of rental housing conditions, she said. “Licensing helps us begin to fill in those gaps.”Des Moines, Iowa, also requires landlords to register their rental properties, get them inspected and obtain a rental housing certificate. It covers housing code requirements, landlord-tenant law, compliance with the federal Americans with Disabilities Act, and other responsibilities tied to operating rental housing.