Widespread instances of overcrowding and slum growth have for many years focused government attention on urban housing problems. Local authorities have statutory responsibility for housing and housing management. The Zambia National Building Society makes loans to local agencies for the financing of approved schemes and the National Housing Authority established a special fund to support self-help projects for low-income earners. One program gives land-ownership to certain residents in recognized informal settlements, thus giving them legal status to build more permanent structures. Mining companies have constructed townships for the families of African workers in the Copperbelt. According to the latest available information for 1980–88, total housing units numbered 1,410,000 with 4.9 people per dwelling.