Geodetic marks are reference points established on the surface of the earth by state, local, and federal agencies. The geographic location of these reference points has been established with extreme accuracy, frequently to a fraction of an inch or so. Geodetic marks are used as starting points for land survey, map making, engineering, construction, environmental measure ments and geological studies. Roughly 1 million of these marks have been selected by the National Geodetic Survey Division (NGSD) to be included in the National Spatial Reference System (NSRS), sometimes called the "net". Maintenance and preservation of these marks is of utmost importance to users of the net and to NGSD, recognizing that many valuable geodetic marks are destroyed by construction, new roads, erosion, or for other causes. Our job is to locate each of these marks and report their condition together with any change in the directions needed to locate them.
     Generally, the mark (or "station", as it is sometimes called) can be a water tower, a building, a monument,  or even a nautical aid to navigation. Normally, however, the mark is a round bronze disc, roughly 3 inches in diameter, firmly imbedded in a square, rectangular, or cylindrical concrete post usually at ground level or several inches below the surface, though it may be above ground level as well. Sometimes the mark is set directly in bedrock, and frequently it is found in the form of a rod enclosed in a plastic pipe.
     Geodetic stations are generally found along roads, highways, property lines, etc., though many times they are found on high ground such as hills and mountain tops. Each station has a unique designation, generally having local significance to near-by residents, places, or business establishments. You need to know the names of each station along a specific search route in order to locate the corresponding description provided by NGS. Descriptions contain directions needed to locate each station and may include distances along roads or from local landmarks or reference points, nearby houses, intersections, trees, culverts, bridges, telephone or power poles, fences, gates, etc.
Geodetic mark recovery is a valuable service to NGSD. participation is interesting, challenging, personally satisfying and always brings a sense of accomplishment.



Transportation is generally by automobile since most marks are located along roads and highways. Sometimes, you will have to hike to remote locations well removed from easy access by automobiles and sometimes marks are accessible only by boat.



Determine and record the condition of the mark as follows:

NGS Searchable Database (Nationwide)

NGS Searchable Database (Nationwide) - Use this link to find all markers within 2 miles of your house or location (you'll need your latitude and longitude, see below. Use the second link to print the information on a single PID.

NGS Data Sheet By Area, a Single PID Data Sheet

Resources for determining your latitude and longitude

Here are some ways to determine your latitude and longitude.

If you need to convert Lat/Lon from decimal format (ex N40.260302 or N40260302) to Degrees/Minutes/Seconds format (N40 Degrees, 15 Minutes, 37.0872 Seconds or 40 15' 37.0872), a converter can be found at:


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