Green Valley Ranch was annexed to Denver from Adams County in September 1973. The original annexation consisted of 3,078 acres, extending from Tower Road to Piccadilly Road and from 38th Avenue to a mile north of 56th Avenue, between Himalaya Road (extended) and Piccadilly Road (extended). The original annexation agreement included a master plan comprising mixed land uses for the area. In 1978, a comprehensive rezoning was adopted which changed the lower density residential uses to medium density residential uses. The rezoning also reconfigured public land sites. In July, 1980 a square mile of land north of 56th Avenue and west of Piccadilly Road was de-annexed from Denver and re-annexed to Adams County as part of a negotiated settlement of a lawsuit brought against the City by Adams County. Development started in Green Valley Ranch in 1981.