Last Updated: Mar 18, 2019 11:25AM EST

Course Measurement and Certification

NYRR scored races are held on USATF-certified courses. The process to certify a course under USATF guidelines is very rigorous and results in an extremely accurate race distance. USATF-certified courses are measured on a bicycle using a Jones Counter, which is calibrated against a steel measuring tape. Courses are verified by multiple measurements, often in sections, performed while following the tangents on the road. More information regarding the certification process can be found on the USATF website.

If you use a personal GPS device when you race, you may notice discrepancies between the USATF-certified race distance and the distance recorded by your device. GPS devices are accurate only up to about 10 meters and must acquire a signal from multiple satellites in order to activate. A device records the wearer's position every 1–20 seconds, and then "connects the dots" to estimate distance. Devices do not take into account changes in elevation, and they are affected by such factors as cloud cover, mountains, tall buildings, and tree cover, all of which can alter measurement.

In addition, a USATF-certified course is measured as the shortest distance between the start and finish and doesn't account for movement outside that, such as moving toward and away from a fluid station. Most runners therefore travel farther than the certified race distance. 

If the time on your GPS device is different from your official race time, consider these factors:
  • If you didn't start and/or stop your device exactly at the time you crossed the start and finish lines, your time will be affected.
  • You might be confusing “moving time” with “elapsed time” on your GPS device.
  • If you have Auto-Pause enabled, the time will stop temporarily when you're moving slower than a certain speed threshold, such as when you stop or walk.
  • If there is interference to the GPS signal, such tall buildings lining NYC streets, your watch may record you as back-tracking or not moving, triggering Auto-Pause.

Read this Runner's World article for more on this topic.