 The third approach is to require that all new development on the urban fringe of existing metropolitan areas is at higher densities than the current average for those cities.The term "urban consolidation" first appears in social science and urban planning literature around the late 19th and early 20th centuries.Much of the existing literature on urban consolidation comes from Australia; some of the world's first government-official urban consolidation policies were enacted in Sydney and Melbourne to increase construction of higher-density terrace housing in the late 19th century.