This layer contains detailed outlines of Maryland counties. The Maryland land county boundaries were built using political county boundaries and the National Hydrology Data (NHD). Land boundaries are a key geographic featue in our mapping process.

Polygon layer contains generalized outlines of Maryland counties.

Polygon layer contains generalized outlines of Maryland counties.

The Maryland county boundaries were built using the USGS Topo Quads, county boundaries from the county governments, monument points, and historic records from the Maryland Archive. This layer has been dissolved from the County Boundaries layer.

The Maryland county boundaries were built using the USGS Topo Quads, county boundaries from the county governments, monument points, and historic records from the Maryland Archive. This layer has been dissolved from the County Boundaries layer.

Polygon features which represent the political boundary of each county in the State of Maryland. The Maryland Political County Boundaries were developed using USGS Topo Quads, boundaries submitted by each Maryland county, monument points, and historic records from the Maryland Archive. This data is used by various modules throughout the Maryland Department of Transportation (MDOT), as well as many other State and local government agencies for purposes such as planning, land use, transportation, data & asset collection, and cartographic product development. This data is updated and published on an annual (yearly) basis for the prior year. This data is for the year 2015. For additional information, contact the MDOT SHA Geospatial Technologies Team: GIS@sha.state.md.us

Polygon features which represent the political boundary of each county in the State of Maryland. The Maryland Political County Boundaries were developed using USGS Topo Quads, boundaries submitted by each Maryland county, monument points, and historic records from the Maryland Archive. This data is used by various modules throughout the Maryland Department of Transportation (MDOT), as well as many other State and local government agencies for purposes such as planning, land use, transportation, data & asset collection, and cartographic product development. This data is updated and published on an annual (yearly) basis for the prior year. This data is for the year 2015. For additional information, contact the MDOT SHA Geospatial Technologies Team: GIS@sha.state.md.us

This layer contains data concerning the location and characteristics of unconsolidated Quaternary deposits within Frederick county. This geodatabase contains geologic data from Frederick County, Maryland. Data from several geologic quadrangles and two regional scale geologic maps were incorporated into the regional scale geologic feature classes in this geodatabase. Because of the scale of this map, some features were generalized slightly from the quad scale data. Additionally, some corrections were made for accuracy, such as edge matching to resolve "border faults". The source data for this map and geodatabase come from maps published by the Maryland Geological Survey from 2001 to the present, as well as one map published in cooperation with the United States Geological Survey. The source maps are Buckeystown (2001), Catoctin Furnace (2004), Frederick (2004), New Windsor (2004), Point of Rocks (2004), Walkersville (2004), Woodsboro (2004), Middletown (2005), Union Bridge (2006), Funkstown (2009), Keedysville, Shepherdstown, Charlestown, and Harpers Ferry (2009), Myersville and Smithsburg (2009), Hagerstown (2013), Mason and Dixon (2013), Clear Spring and Hedgesville (2014), Williamsport (2014), Blue Ridge Summit (2021, in review), Emmitsburg and Taneytown (2021, in review), all 1:24000 quadrangle scale, as well as portions of two regional maps: Geologic Map of Garrett, Allegany, and Western Washington Counties, Maryland (2013), and Geologic Map of the Frederick 30' x 60' Quadrangle, Maryland, Virginia, and West Virginia (USGS, 2007). The GIS data from the referenced maps were mosaiced in Arc Map, corrected for accuracy across quad boundaries, merged to form a continuous dataset and clipped to the extent of Frederick County. Feature level metadata are included, which contain field descriptions for each feature class. This is a small scale dataset, appropriate for 1:100,000 regional scale. Quad scale data are suggested for display or analysis that requires a larger scale. This dataset is prepared for compliance with the USGS GeMS database standard. Last Updated: 06/01/2022

This layer contains data concerning the location and characteristics of bedrock, mappable geologic units, within Frederick county. This geodatabase contains geologic data from Frederick County, Maryland. Data from several geologic quadrangles and two regional scale geologic maps were incorporated into the regional scale geologic feature classes in this geodatabase. Because of the scale of this map, some features were generalized slightly from the quad scale data. Additionally, some corrections were made for accuracy, such as edge matching to resolve "border faults". The source data for this map and geodatabase come from maps published by the Maryland Geological Survey from 2001 to the present, as well as one map published in cooperation with the United States Geological Survey. The source maps are Buckeystown (2001), Catoctin Furnace (2004), Frederick (2004), New Windsor (2004), Point of Rocks (2004), Walkersville (2004), Woodsboro (2004), Middletown (2005), Union Bridge (2006), Funkstown (2009), Keedysville, Shepherdstown, Charlestown, and Harpers Ferry (2009), Myersville and Smithsburg (2009), Hagerstown (2013), Mason and Dixon (2013), Clear Spring and Hedgesville (2014), Williamsport (2014), Blue Ridge Summit (2021, in review), Emmitsburg and Taneytown (2021, in review), all 1:24000 quadrangle scale, as well as portions of two regional maps: Geologic Map of Garrett, Allegany, and Western Washington Counties, Maryland (2013), and Geologic Map of the Frederick 30' x 60' Quadrangle, Maryland, Virginia, and West Virginia (USGS, 2007). The GIS data from the referenced maps were mosaiced in Arc Map, corrected for accuracy across quad boundaries, merged to form a continuous dataset and clipped to the extent of Frederick County. Feature level metadata are included, which contain field descriptions for each feature class. This is a small scale dataset, appropriate for 1:100,000 regional scale. Quad scale data are suggested for display or analysis that requires a larger scale. This dataset is prepared for compliance with the USGS GeMS database standard. Last Updated: 06/01/2022