The National Housing Act of 1934 established the Federal Housing Administration (FHA) to try to encourage home ownership during the Great Depression, but another consequence was redlining. In 1935, the Federal Home Loan Bank Board (FHLBB) asked the Home Owners' Loan Corporation (HOLC) to assess 239 cities and develop "residential security maps" to indicate the level of security for real estate investments in each surveyed city. Because of older housing in minority neighborhoods and the undervaluation of minority readiness to work and protect their homes, the agency defined certain areas as high risk. That prevented many residents of minority neighborhoods from being able to get mortgages or loans to renovate their properties. Redlining had the unanticipated result of increased residential racial segregation and encouraging urban decay in the United States. Urban planning historians theorize that the maps were later used for years by public and private entities to deny loans to people in black communities.