OldMapsOnline not only provides access to historic maps from all over the world, but also provides interactive features for overlaying maps and exploring maps in the context of historical timelines.

Digitized Land Office patents from 1637-1975.

Maryland State Archives card index to certificates of survey and land patents.

Peerless Rockville is an award-winning nonprofit, community-based organization founded in 1974 to preserve buildings, objects and information important to Rockville's heritage. Peerless Rockville advances its goals through education, example, advocacy, and community involvement. Peerless Rockville takes its name from a real estate promotional booklet published in 1890 to interest city-dwellers in the new Rockville subdivision of West End Park.

The University Libraries' Digital Collections, close to 100 in all, cover a wide range of subject areas, including agriculture, the Civil War era, geology and geography of Pennsylvania, labor history, Pennsylvania history, Penn State history, and political protest. Many of these collections were digitized from holdings in the Special Collections Library.

James Pentland was born in Northern Ireland in 1820, immigrated to Philadelphia in 1832 and arrived in Baltimore City in the 1840s where he established a thriving Florist and Horticultural business. This family was of Scots-Irish descent with branches in Canada and roots in the Presbyterian church. Other families include: Brown, Finnigan, McWatters, Polley and Reese.

The family of William Petticoate has its roots in Anne Arundel County in the 1660s or earlier. This Web site traces descendants into the late 19th century. The family surname is variously spelled Petticoate, Petticourt, Petticoarte, Peddicord, etc. The family migrated from Anne Arundel to Baltimore County and other geogrphic sites.

PLATS.NET is a system developed by the Maryland State Archives, the Administrative Office of the Courts and Maryland Circuit Court Clerks to preserve and make accessible all plats filed with the Land Office and the Circuit Courts of Maryland. The site includes land survey, subdivision, and condominium plats from 1658 to 2023.

The Prince George's County Genealogical Society, founded in 1969, is the oldest Maryland County Genealogical Society in continuous existence. Its objectives are to collect, preserve, and disseminate genealogical knowledge and information, particularly that material that deals with Prince George's County, Maryland. The Society meets virtually September through June except for January. They hold in-person options on occasion; see their website for details.

Founded in l952, the Prince George's County Historical Society works to fulfill its mission of preserving and promoting the County's long and diverse history through reproducing new and out-of-print historical materials, collecting records, documents, photographs, and artifacts reflecting the County's social, economic and political history, operating the Frederick S. DeMarr Library of County History, providing educational opportunities through lectures, programs and tours, and recognizing and supporting individuals and organizations that are making significant contributions to the preservation of the County's rich multi-ethnic, multi-cultural heritage.