Montgomery County, Maryland  

• City of Gaithersburg
• City of Rockville
• City of Takoma Park
• Maryland-National Capital Park and Planning Commission
• Montgomery College
• Montgomery County Public Schools
• Washington Suburban Sanitary Commission

Washington D.C. Metropolitan Area

• Arlington County, Virginia
• City of Alexandria, Virginia
• Fairfax County, Virginia
• Loudoun County, Virginia
• Prince Georges County, Maryland
• Prince William County, Virginia

Organizations using GIS

• American Association of Geographers
• American Forests
• American Society of Photogrammetry and Remote Sensing (ASPRS)
• CIESIN: The Consortium for International Earth Science Information Network
• National Association of Counties (NACo)
• National Center for Geographic Information and Analysis (NCGIA)
• National Geographic Society
• OpenGIS Consortium, Inc.
• The Association for Geographic Information
• Urban and Regional Information Systems Association (URISA)

State of Maryland

• Baltimore County, Maryland GIS
• Carroll County, Maryland GIS
• Maryland Department of the Environment
• Maryland Geological Survey
• Maryland Historic Trust
• Maryland Office of Planning
• Maryland State Highway Administration
• Maryland State Government Geographic Information Coordinating Committee
• MERLIN On-line Map Maryland Your Way

Federal Government

• Chesapeake Bay Program
• Environmental Protection Agency - GIS
• Federal Geographic Data Committee
• NASA Global Change Master Directory
• NASA Earth Observing Systems (EOS)
• NASA Distributed Active Archive Centers
• NOAA National Geophysical Data Center
• NOAA Satellite Active Archive
• United States Census Bureau
• United States Department of Transportation - GIS
• United States Fish and Wildlife Service
• United States Geological Survey (USGS) Mapping Standards
• United States National Park Service
• United States Natural Resources Conservation Service
• USGS Earth Resources Observation Systems (EROS) Data Center
• USGS - Maryland Office
• USGS - Patuxent Wildlife Research Center