Second time doing this one! I used my GPS watch and back-up GPS on a phone (just in case something went wrong). I highly advise people do the same. Just after the marathon mark, we had to stop and let a bunch of cars go by before crossing a road. Out of habit, I stopped my watch, but completely forgot to restart it until about 10 minutes later. My strava data has the correct elapsed time (3:31:18), but my distance is a little short (due to the watch being stopped for 10 minutes). The other GPS file attached confirms the correct distance (around 31.5 miles). Despite this, my watch data confirms that I started and stopped at the correct spots (over the bridge on Lake Cook Road to the trailhead near the IL/WI border) and ran the entire length of the trail. There is a just a short stretch from around mile 26-28 where it wasn't counting distance.
The Warren High School boys team ran a solid stretch with me through Gurnee and Steven Anderson biked alongside me, carrying water, electrolyte tablets, and gels.
This is an awesome trail! I highly encourage more people to do it.