The article explains how the concept of 'land use planning' in American urban planning evolved over time. Initially, city planners saw cities as collections of public facilities, but later began to focus on land use and population density. Land use planning originated from rural county planning and was first used as a guide for zoning in urban areas in the 1930s. It then influenced urban redevelopment policies in the 1940s before becoming fully integrated into city planning in the 1950s and 1960s.