Selden Island is a 408-acre island in the

Potomac River The Potomac River () drains the Mid-Atlantic United States, flowing from the Potomac Highlands into Chesapeake Bay. It is long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map. Retrieved Augus ...

, located about WNW of

Washington, DC ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan ...

. It is about 4 km long and 0.4–0.5 km wide (2.5 x 1/4–1/3 miles). Although it is located within

Montgomery County, Maryland Montgomery County is the most populous county in the state of Maryland. As of the 2020 census, the county's population was 1,062,061, increasing by 9.3% from 2010. The county seat and largest municipality is Rockville, although the census-design ...

, the only road access is via a bridge connecting it to the

Loudoun County, Virginia Loudoun County () is in the northern part of the Commonwealth of Virginia in the United States. In 2020, the census returned a population of 420,959, making it Virginia's third-most populous county. Loudoun County's seat is Leesburg. Loudoun C ...

side of the river. Archaeological evidence indicates the island has been a site of human activity since the Early

Woodland period In the classification of :category:Archaeological cultures of North America, archaeological cultures of North America, the Woodland period of North American pre-Columbian cultures spanned a period from roughly 1000 Common Era, BCE to European con ...

, around 1000 BCE. A characteristic type of

pottery Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and por ...

known as Selden Island ware dates from this period. It is also the site of a significant Late Woodland period settlement known as the Walker Prehistoric Village, which was added to the

National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

in 1975. In 2002, following the diagnosis of two Loudoun County teenagers with

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...

, mosquitoes from the island were found to carry the ''

Plasmodium vivax ''Plasmodium vivax'' is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria. Although it is less virulent than ''Plasmodium falciparum'', the deadliest of the five huma ...

'' malarial parasite. In 2004, Selden Island was purchased by the

Howard Hughes Medical Institute The Howard Hughes Medical Institute (HHMI) is an American non-profit medical research organization based in Chevy Chase, Maryland. It was founded in 1953 by Howard Hughes, an American business magnate, investor, record-setting pilot, engineer, fil ...

as an addition to the

Janelia Farm Research Campus Janelia Research Campus is a scientific research campus of the Howard Hughes Medical Institute that opened in October 2006. The campus is located in Loudoun County, Virginia, near the town of Ashburn. It is known for its scientific research and m ...

. It was formerly leased as a sod farm.

References

{{authority control Archaeological sites in Montgomery County, Maryland Islands of the Potomac River River islands of Maryland Landforms of Montgomery County, Maryland