Topographic Maps

Topographic maps are two-dimensional representations of the physical and cultural characteristics of the earth's surface. Their main purpose is to show elevation of the terrain by differentiating the physical features of the landscape (mountains, valleys, plains, shorelines, etc.). This differentiation is achieved by the use of contour lines, or lines of equal elevation, the spacing of which indicates the slope of the land - the closer the contours, the steeper the slope. These maps also show other land features such as waterways (streams, rivers, ponds) and vegetated areas, as well as various cultural features (towns and cities, road and railways, power lines, political boundaries, etc.). Topographic maps are used for both professional applications (e.g., urban planning, road construction, geologic/environmental studies) and for recreational purposes (e.g., hunting, fishing, camping, and biking). Topo maps are produced in several sizes and scales to fit the user's needs.

Topographic maps made and published by the U.S. Geological Survey (USGS) are now available from the USGS online. This includes standard historical and current maps as well as custom versions. They are available as digital downloads and/or hard copy (printed map) orders: https://www.usgs.gov/programs/national-geospatial-program/topographic-maps.

The Maryland Geological Survey (MGS) sells or distributes three types of topographic maps in paper form, all of which are now considered historical or legacy publications:
1) historical county topographic maps, which were prepared by MGS (published between 1973 and 1993);
2) old versions of 7.5-minute (or 7.5') quadrangle topographic maps, which were prepared by the U.S. Geological Survey (USGS); and
3) a Maryland-Delaware topographic map published in 1990, also prepared by the USGS.

[Note: "minute" is a unit of angular measure, in this case units for latitude and longitude. In angular measures, the following relationships apply: 1 degree (or 1°) equals 60 minutes (60' ), and 1 minute (1' ) equals 60 seconds (60").

• Historical MGS County Topo Maps

  Scale - 1:62,500 or 1/62,500 (1 unit on the map = 62,500 units on the ground)
  

  or 1 inch on the map equals approximately 1 mile on the ground.
  Each map encompasses one full county; there are 23 counties in Maryland.
  Paper copies of the historical county topo maps may be purchased over-the-counter or by mail, while supplies last.
  pricing information



• USGS 7.5-minute Quadrangle Topo Maps (old paper versions)

  Scale - 1:24,000 or 1/24,000 (1 unit on the map = 24,000 units on the ground)
  

  or 1 inch on the map equals 2,000 feet on the ground.
  The average quad in Maryland covers an area of approximately 6.7 x 8.6 miles (roughly 58 square miles), or 7’30” (7 minutes, 30 seconds = 1/8 degree) of latitude by 7’30” of longitude; a 7.5-minute quad covers a much smaller area than any of Maryland's county topo maps. Complete coverage of Maryland requires all or part of 256 7.5-minute quads.
  A limited number of paper copies of the historical USGS quadrangle maps are sold over-the-counter or by mail, while supplies last.
  pricing information



• USGS Topographic Map of Maryland and Delaware (1990)

  Scale - 1:500,000 or 1/500,000 (1 unit on the map = 500,000 units on the ground)
  

  or 1 inch on the map approximately equals 8 miles on the ground
  Paper copies of this 1990 map may be purchased over-the-counter or by mail, while supplies last.
  pricing information

The scale of a 7.5-minute quad map is larger than the scale of a county topo map, which is in turn larger that the scale of the State map. (1/24,000 > 1/62,500 > 1:500,000) The larger the scale, the more detail can be shown. However, to keep the map at a convenient size, the larger the scale, the less geographic area can be depicted.

For more information regarding topographic maps or geologic topics, visit the Maryland Geological Survey website or contact the Maryland Geological Survey, 2300 St. Paul Street, Baltimore, Maryland 21218-5210; phone (410) 554-5500.

Compiled by the Maryland Geological Survey, 2300 St. Paul Street, Baltimore, MD 21218
This electronic version of "Fact Sheet No.4 " was updated and revised by the Maryland Geological Survey in 2024.