The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run logo
running

The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run

Date
October 10, 2026
Distance
100K Ultra Trail Run · 50K Trail Tun · 25K Trail Run & more

From the Organizer

Get ready for The Mammoth Race Glen Rose FALL migration. This multi-distance trail run welcomes families and runners of all skill levels. Enjoy the Hill Country that surrounds this stunning ONE THOUSAND acre ranch. We can't wait to see you out there! 

The Mammoth - Glen Rose, TX is a multi-distance trail running event located on the trails High Hope Ranch and Eco-Retreat. Distances offered are 100K, 50K, 25K, 10K, 5K and The Mighty Mammoth 1K FUN RUN. There will be two sections of the course: a 3.5-mile loop and a 7-mile loop. Both loops combined equal a 10.5 mile lap. The event will run from 7 am on Saturday morning until 9 am on Sunday morning. The starting line and Main Race Hub will be the main lodge on the Ranch. There are two aid stations on course: the main lodge at the starting line, and Matazamo ranch house. Aid stations are approximately 3.5 miles apart.                                                                                                                                                                                                                                                                                       
RACE CATEGORIES:

  • 100K - 26hr Cut-off time
  • 50K 
  • 25K 
  • 10K 
  • 5K   
  • Mighty Mammoth 1K Fun Run - NON-CHIP TIMED EVENT

RACE HIGHLIGHTS:                                                                                                                                                                                                       

  • Finisher Shirts and Medals
  • Generous Cut Off times - Cut off time for 100K only!
  • Finisher BUCKLES for 100K Ultra
  • Scenic routes through pristine natural landscapes
  • Well-marked trails and 'round the clock aid stations
  • Exclusive sites for tent camping and boondocking (no hook-ups)
  • Post-race celebration. Music, food and refreshments!

ADDITIONAL INFO:

  • PETS ARE NOT ALLOWED. USATF sanctioned event policy does not allow for animals to participate in competitions.
  • The Mammoth is an Enviro-Friendly Event - B.Y.O.B (Bring Your Own Bottle) 

​RAIN or SHINE. In the event of inclement weather that would threaten the safety of the racers, the event or courses may be altered or the event may be delayed or canceled. 

RACE DAY SCHEDULE

  • 100K  -  07:00am
  •   50K  -  07:15am  
  •   25K  -  07:30am
  •   10K  -  07:45am
  •    5K   -  08:00am
  •    1K   -  10:00am

CLASSIC SWAG​

  • All participants will receive a Mammoth Race OFFICIAL Race shirt and a Finisher's Medal. 
  • Finisher BUCKLES for 100K ULTRAS 

AWARDS​

  •  NO PLACE FINISHER AWARDS. BRAGGING RIGHTS ONLY 

PACKET PICK-UP

  • RACE DAY on site
    ​​

PARKING

  • Price INCLUDES Entrance and Parking

OVERNIGHT CAMPING

  • $10 per PERSON. NOT included in registration. Max 6 people per site. PAYABLE AT THE GATE

REFUNDS/TRANSFERS

  • Race Entry Fees are NON-REFUNDABLE, however TRANSFERS to another Person, Category or Mammoth Event are allowed.

COURSE MAPS - Viewable HERE

Distances & Pricing

100K Ultra Trail Run7 AMRegister →
50K Trail Tun7:15 AMRegister →
25K Trail Run7:30 AMRegister →
10K Trail Run8:30 AMRegister →
5K Trail Run9 AMRegister →
The Mighty Mammoth 1K Fun Run11 AMRegister →
PACER - 100K Ultra Trail Run7 AMRegister →

Race Location

About This Sport

From Endurance Grid's Founder

Endurance Grid is here to help you understand the sport, decide if it's the right fit, and learn how to prepare. For course distances, logistics, and race-day specifics, always defer to the race organizer's event page.

The 10K is the distance where running stops feeling like a starting point and starts feeling like a sport. Long enough to require a real training block. Short enough that race day is fully manageable for a first-timer who's put in the work.

Race day energy at a 10K is community at its best — strangers cheering you by name, people moving toward the same goal, an atmosphere that solo training can't replicate. It's fast enough that you'll spend the whole race pushing rather than managing your effort.

This is also the distance that builds the base for everything else. Most athletes who go on to run half marathons, do triathlons, or compete in HYROX started here. What you need: running shoes fitted to your stride, a training plan, and the race on your calendar. The registration is what makes the deadline real.

How long to train: 4–8 weeks for most fitness levels.

Running

From 5K to marathon, running races are the most accessible entry point into endurance sport. There's a distance for every fitness level and a community at every start line.

Frequently Asked Questions (FAQs)

What is The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run?
The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run is a running event held in Glen Rose, TX. Learn more about the different endurance sports here.
When and where is The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run?
Saturday, October 10, 2026 in Glen Rose, TX at High Hope Ranch and Retreat Center, Glen Rose, TX. Check the official event page for exact start times and wave schedules.
How do I register for The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run?
Registration is handled through their official registration page. Confirm pricing, distances available, and sign up there.

The Mammoth 2026 - 100K / 50K / 25K / 10K / 5K and Mighty Mammoth 1K Fun Run

Oct 10, 2026

Register →