Dinosaur Valley Endurance Run

The Dinosaur Valley Endurance Run is a weekend of loops in Dinosaur Valley State Park outside Glen Rose, southwest of Fort Worth. Everything turns on one hilly 10.5-mile loop of double track and wooded single track, rocky in places, with two aid stations, Fence Line out on the course and Cedar Brake at the start and finish in Valley Village. The 50K runs it three times and the 100K six. The 100 mile runs it nine times and then finishes on a five-mile loop, with about 9,000 feet of climbing by the organiser's figure.

There is no final time limit. The race sets incremental cutoffs through Sunday instead, the last of them at 5 p.m., and once a runner makes it the finish waits for them. A 100-miler who reaches the end of the sixth loop is credited with a 100K finish and can win a 100K award, so the 100K results always carry some of the 100-mile field. The 2026 edition, the tenth, starts on Saturday, November 21: the 100 mile and 100K at 7:00 a.m. Central and the 50K at 8:00. Entry is first-come on UltraSignup, and the 100 mile and 100K are both Western States 100 qualifiers.

A 10.5-mile loop in Dinosaur Valley State Park, run three times for the 50K and six for the 100K; the 100 mile does nine and then a five-mile final loop. The organiser gives approximate climbing of 9,000 feet for the 100 mile, 5,700 for the 100K and 2,900 for the 50K, on double track through fields and single track in the woods over packed dirt, rocks, slick rock and some roots. The river crossings were taken out in 2018, and the course has been the same since. The two aid stations, Fence Line and Cedar Brake, are cupless, and a 100-miler passes them 28 times. Cutoffs fall on the Sunday: everyone except the 100 mile must have started a final loop by 12:30 p.m., the 100 mile must be through Cedar Brake at mile 84 by then, and the last cutoff for every distance is leaving Fence Line for the finish by 5 p.m.

Entry is first-come on UltraSignup, with prices rising in tiers as each distance fills and no lottery or qualifying race. For 2026 it opened on December 15, 2025 and closes on November 18, with the 100 mile capped at 180, the 100K at 200 and the 50K at 150; the 100K and 50K had sold out by early November and were taking waitlist names until November 14. There are no drop-downs between distances during the race.