Prioritized Marks

Currently there are over 400,000 bench marks across the Conterminous United States (CONUS), Alaska, Hawaii and U.S. territories. Tidal marks and bench marks are used for determining heights and when possible providing GPS on these marks can help to relate the GPS derived ellipsoid height with the leveling derived orthometric height associated with these marks.

NGS will create models and tools that cover the nation using the data we have. The information provided on this page will enable local users to collect and submit data that will improve the accuracy of those products in their local regions.

Over the past year NGS has analyzed the leveling and GPS data we have on bench marks to determine where additional data would be most helpful in creating the next hybrid geoid model, GEOID18 and the transformation tools that will be produced with NAPGD2022. This rigorous analysis examined the ellipsoid-orthometric-geoid relationship at over 30,000 individual bench mark as well as the patterns in that relationship over broad regions. A prioritized list of bench marks where additional GPS data would be most helpful has been generated from that analysis and is available to download below.

Download Prioritized Marks

A listing of prioritized marks has been generated and is downloadable in various formats (.xls; .kmz; and .shp). There are approximately 5700 benchmarks in this listing. Click the icons to the right to download the files.

Files updated: October 2, 2018

Priorities A and B

The marks in the list are coded as either Priority A or B and both A and B priority marks will help improve the development of GEOID18 as well as support development of the transformation tool for NAPGD2022. Here is more information about the differentiation between the two priorities.

Help the Local Surveying Community by Submitting Mark Recoveries

When going out to recover a bench mark please submit mark recoveries and photos using DSWorld. Handheld GPS coordinates are sufficient to submit a mark recovery note. Submitting mark recoveries will help local surveyors to know that a mark is still there and what condition it is in. See the Recover web page for more information on submitting recoveries.

Participating in National Surveyors Week

Supporting any GPS on BM objective is encouraged during National Surveyors Week. It is an excellent opportunity to raise the profile of the surveying profession and improve the National Spatial Reference System at the same time.

Web Map / Tracking

The 2018 Web Map was created to show the locations of prioritized marks and will keep track of when OPUS solutions are submitted. This will be the best place to go check out any marks you are considering observing since this will be updated weekly to provide the most up to date information for data that has been collected in this years GPS on Bench Marks Campaign.

Superceded Priority Lists

As we continue to have the map updated we will update these files to include the marks that have been completed or unusable when mark recoveries are submitted.