The National Geodetic Survey's
"GPS on Bench Marks" Campaign

I’m Brad Kearse, acting director of the National Geodetic Survey (NGS), the agency responsible for maintaining and modernizing the National Spatial Reference System (NSRS), a consistent coordinate system that defines latitude, longitude, height, scale, gravity, orientation, and shoreline throughout the United States.

I’d like to invite you to take part in the NGS GPS on Bench Marks campaign. Anyone can participate in survey mark hunting by finding nearby survey control bench marks — brass or metal disks in the ground that provide latitude, longitude, and height data — on the GPSonBM Priority Map and submitting recovery reports using the new Beta Mark Recovery Form. Geospatial professionals can contribute further by observing the priority marks with survey-grade GPS equipment and sharing their results using NGS’s Online Positioning User Service (OPUS). Please be sure to stay at least six feet away from others while you’re out searching for bench marks to protect yourself and others from COVID-19.

GPS on Bench Marks is a crowd-sourced data collection campaign where users report current information on the status of local bench marks and share GPS observations on those marks to improve the local accuracy of NGS national scale models and tools. Over the past century, NGS surveyors have walked across the country making very precise height measurements on more than 400,000 bench marks within the conterminous United States, Alaska, Hawaii, and the U.S. territories. 

NGS has now prioritized about 77,000 of those bench marks where GPS observations would be most valuable. The GPSonBM Priority Map displays these prioritized marks and identifies the geographic area where that data will improve the NGS tools so users can target data to improve the tools in the areas where they work.

You can help move the nation toward a modernized NSRS by recovering a bench mark, observing and collecting GPS observations, and reporting data back to NGS. I encourage you to contribute to the GPS on Bench Marks campaign!

For the latest news, subscribe to our GPSonBM email list (the subscription option is on the left-hand column of the page), and check out NGS’s February 2020 webinar: GPS on Bench Marks: 2022 Transformation Tool Campaign Update. To learn about using the GPSonBM Priority Map, check out NGS’s July 2019 GSPonBM webinar.

Thank you,