Dunthorpe is an affluent unincorporated suburb of Portland, Oregon, United States. It is located just south of the Portland city limits and north of the Multnomah County line on the west side of the Willamette River. Lewis & Clark College, Tryon Creek State Park, and Lake Oswego are nearby. Since 2020, it has been designated as a Census Designated Place Demographics History In January 1916, William M. Ladd's Ladd Estate Company purchased from the soon to be dissolved Oregon Iron & Steel Company for $1. The company drafted very specific provisions for the Dunthorpe development, including: Only residential buildings were allowed, except for outbuildings to house domestic animals; Swine and goats were prohibited; The minimum cost of a house was $3000; No residence could be used or occupied by "persons of African or Mongolian descent" unless they were employed as servants of the masters; and the sale of "intoxicating liquor" was also prohibited. Arts and culture Museums and other points of interest One of the notable attractions of the area is the Elk Rock Gardens of the Bishop's Close, an estate which consists of on a high bluff on the western bank of the Willamette River. The property includes approximately of cultivated English-style gardens that were designed by the New York firm of Olmsted and Son, who also designed Central Park in New York City. The garden is open to the public seven days a week and is widely known for the many varieties of magnolias as well as for examples of many other native and exotic plants. Education Riverdale School District in Dunthorpe is among the best academically performing school districts in Oregon by various measures, including standardized test scores, which are frequently the best in the state. According to 24/7 Wall St.'s analysis of U.S. Census data from 2006 through 2010, the Riverdale School District is the third richest school district in the United States. As a community, Dunthorpe was historically anchored by Riverdale Grade School. In the early 1990s, the Oregon legislature decreed that all school districts should have both primary and secondary schools, and expected smaller school districts like Riverdale to merge. While an old grade school was purchased and renovated for use as Riverdale High School, high school students were bussed to nearby Marylhurst University in the neighboring city of West Linn, where space was leased by the school district. In September 2002, the high