The Oxon Hill Manor/ Addison Plantation site (18PR175) is a late 17th-19th-century plantation overlooking the Potomac River in western Prince Georges County. The site contains the remains of the original Oxon Hill Manor, which was constructed in 1710-1711 and burned in 1895. Brick and granite ruins associated with the house foundation and subsurface features have been the focus of numerous archaeological investigations since 1979.

Acquired by John Addison in 1687, the property was the home of successive generations of the Addison family until 1810, when Walter Dulaney Addison sold most of the original estate to Zachariah Berry. The Berry family sold the manor house and the bulk of the land to Samuel Taylor Suit in 1888. The property had numerous owners over the next few years until the manor house burned in 1895. Sumner Welles, Undersecretary of State during Franklin Roosevelt’s administration, purchased 245 acres of Oxon Hill Manor in 1927 and built a large house approximately one-third of a mile from the ruins of the colonial dwelling. The Maryland-National Capital Park and Planning Commission, Department of Parks and Recreation now owns the extant mansion and 55 acres of the original tract.

Archaeological Investigations

Preliminary reconnaissance surveys of the Addison Plantation for the Maryland Department of Transportation identified the site as a potentially significant archaeological resource. Intensive survey was subsequently undertaken under the direction of Richard J. Dent. As a result of this survey, the site was determined eligible for the National Register of Historic Places, and a proposed highway interchange was realigned to reduce construction impacts to the site. Subsequently, additional surveys of the realigned highway right-of-way were conducted by Silas Hurry and Maureen Kavanagh.

Data recovery excavations were undertaken in the highway right-of-way by Garrow & Associates in 1985. The major focus of research during this project included the archaeological investigation of the worldview of the inhabitants, the social status expressed at Addison Plantation, the relative wealth of slaves on this plantation compared with slaves of less wealthy planters, market choices of the residents through time, and the prehistoric component at the site. The site exhibited the type of formal, hierarchical use of space associated with the Georgian mindset, but due to the limited area of the investigation, many of the research questions could not be completely addressed.

Other archaeological investigations have included a general survey by Garrow & Associates of cultural resources on a ridge spur at the site. Although this survey defined 19 archaeological loci, the property was not systematically examined. In addition, two test excavation projects at the Addison Family Cemetery (18PR176) and a test excavation project at the mausoleum (18PR177) were conducted. Test excavations at the Addison Family Cemetery identified a total of 15 burials, and suggested that 15 to 25 additional burials may be present. The mausoleum investigations revealed extensive recent disturbance and no evidence of burials. Archaeological investigations were also conducted on selected road tracts for the PortAmerica construction project. The examination of the proposed roadways yielded no significant remains.

In 1987, John Milner Associates conducted Phase II investigations of the Addison Plantation site, including intensive testing of the manor house foundations, in order to locate and evaluate significant archaeological resources. In addition, a Phase I survey of the remainder of the Beltway parcel was undertaken. A total of 637 shovel test pits, 51 1x1m test units, and 77.4 square meters of backhoe trenches were excavated as part of the survey. In addition 25 1x1m test units were excavated in order to test the manor house foundations and related structures. Sixteen areas and subareas of archaeological material concentration were thus identified. All these site areas were expected to be adversely affected by the PortAmerica Development Project, so Phase III investigations were begun. However, PortAmerica ran into financial difficulties, so the archaeological project was never fully completed.

Archeobotanical Studies

Garrow & Associate's 1985 data recovery project included ethnobotanical analysis of Area I, located to the north and adjacent to the manor house ruin.

Five general contexts were rigorously sampled, including well, cellar, meathouse, and structural features. Original soil volumes were not recorded, and archeobotanical analyses were limited to seeds recovered through flotation. The seed assemblage was predominantly uncarbonized, with only 25 carbonized seeds recovered site-wide. 25,097 non-carbonized seeds were recovered, including a great variety of interesting ornamental garden plants, tree species, crops, and herbs.

While non-carbonized seeds are often considered modern intrusions to open-air archaeological sites, unburned seeds are important artifacts from certain kinds of historic features, such as wells and privies. Many of the contexts sampled at the Addison Plantation contained concentrations of economically important plants.

Arboreal species documented at the site include hickory, black locust, and honey locust. Seeds of ornamental and edible garden plants include jimsonweed, bedstraw, Solomon’s seal, sweet pea, violets, larkspur, amaranth, spurge, and milkweed. Herbs useful in colonial medicine were also well-documented, with mustard, clover, purselane, cow parsnip, poke, pennycress, chickory, coriander, and chamomile identified. Grape, cherry, plum, strawberry, elderberry, blackberry, and peach represent the remains of orchard fruits. And a concentration of flax seeds (approximately 22,000 from a single context) document that this source for linen fiber was important to the economy of the plantation.


Garrow, Patrick H. and Thomas R. Wheaton, Jr.
1986 Oxon Hill Manor Archaeological Site Mitigation Project. Garrow & Associates, Inc. for the Maryland
State Highway Administration.
Garrow, Patrick H.
1986 Oxon Hill Manor Plantation, 1710/11-1895. Garrow & Associates, Inc. for the Maryland State Highway Administration.

Thank you for visiting our web site. If you have any questions, comments,
or new information to share, please contact us at