Ralston Creek Half-Marathon
& 5K Run

February 19, 2023
Arvada, Colorado

The Ralston Creek Half Marathon and 5K are back in 2023 and we are excited to announce the Racing Underground Winter Running Series also returns after a 2 year hiatus due to the COVID pandemic! Join us at Colorado's Premier Winter Half Marathon.

The Ralston Creek races feature a fun winter half-marathon and 5K run conveniently located on the west side of the Denver Metro Area in Arvada, Colorado. The courses covers a scenic mix of road and bike path over rolling terrain, and an optional early start time for half-marathon runners who expect to take more than 2.5 hours to complete the course!


HALF-MARATHON COURSE:The Ralston Creek Half Marathon course follows a mix of roads and bike paths on the west side of Arvada. The opening 5 miles are fairly flat, with a barely noticeable gradual gain in elevation. Miles 5 through 6.5 are rolling, with one good climb leading to the high-point of the course atop Ralston Mesa at 7.75 miles. From there, the course is almost all downhill and flat to the finish, with the exception of a small bump around mile 9 and a very gradual uphill in the last half-mile. Click Here for a Half-Marathon Course Map

Half-Marathon aid stations are located approximately every two miles throughout the course (approximate locations are: 2.25, 4.25, 6.5, 9.5, 11.5) All aid stations will have both water and Skratch energy drink. Hammer Gel will be available at miles 4.25 and 9.5.

5K COURSE:The Ralston Creek 5K Run course follows a mix of roads and bike paths on the west side of Arvada. The route starts with a slight downhill in the opening mile, a flat second mile, and a very gradual uphill in the final mile. A single aid station will be located at approximately halfway into the 5K run. Click Here for a 5K Course Map


Runners Roost Lakewood

The Ralston Creek Half Marathon serves as the final race in the Racing Underground winter running series which returns after a 2-year COVID hiatus. The series has been extremely popular, selling out two of the three events every year!

The three-race series includes the Stocking Run 5K in December, the Yeti Chase 5K/10K in January, and the Ralston Creek Half-Marathon & 5K in February. Choose from the 5K-5K-5K series or the 5K-10K-Half Marathon Series, and save 10 percent on your entry fees when you choose the Race Bundle option.


The Ralston Creek races have three start waves. Waves 1 & 2 are for the half marathon runners. Wave 3 is for 5k runners.

Start Procedure & Cutoff Times: Racing Underground utilizes a 2-wave start procedure for its half marathon distance events - the 'Official' start time, and an optional 'Early' start time for athletes who will take more than 2 hours and 45 minutes to complete the course.

The Official start time for the Ralston Creek Half Marathon is 9:45am. The optional Early Start time is 9:00am. All runners and walkers must complete the course by 1:30pm. This means early starters have 4 hours 30 minutes to complete the course, and 9:45am starters have 3:45 to finish. All official finishers, regardless of wave, will be listed in the official results and will receive a finisher medal.

Why do we do this? There are two reasons why we use this two wave start procedure. First, the early start allows our slower runners to enjoy a better finish line experience, with more spectators on hand to cheer them in. The second reason is for course logistics.

There are no requirements to enter the 9:45am start, except that you must finish faster than 3 hours 45 minutes. If you are a 3:30 half marathon runner and you would like to start in the 9:45am wave, then you are welcome to start in the 9:45am wave.

The 9:00 Early Start requires that you MUST take longer than 2 hours 30 minutes to complete the course. If there is even a small chance you will run faster than 2:30, then you should start in the 9:45am wave. Early starters who run faster than 2:30 will not appear in the race results.

A 2:30 half marathon time is roughly an 11-minute and 30 seconds per mile pace.

  • 7:30 a.m. - Packet Pick-Up Opens
  • 9:00 a.m. - Wave-1 Start (half-marathon runners expecting to be on the course longer than 2 hours 45 minutes)
  • 9:45 a.m. - Wave-2 Start (half-marathon runners expecting to take less than 2 hours 45 minutes)
  • 10:00 a.m. - Wave-3 Start (all 5K runners)
  • 10:45 a.m. - 5K Awards Presentation*
  • 11:30 - Half-Marathon Top-3 Overall Awards Presentation*
  • 1:30pm - Finish Line Cutoff

  • 5k Overall Awards will be based on GUN TIME. An awards presentation for our top overall 5k finishers will take place at 10:45am.

  • 5k Age-Group Awards will be based on NET TIME. They will be presented immediately following the presentation of awards to our top overall finishers.

  • Half Marathon Overall Awards will be based on GUN TIME. An awards presentation for our top overall Half Marathon finishers will take place at 11:30am.

  • Half-Marathon Age-Group Awards will be based on NET TIME. Following the presentation of awards to our top overall finishers, age group awards winners may stop by the awards tent to pick up their awards as category awards have been confirmed. The awards tent will receive updated awards lists throughout the morning.

  • Raffle prizes will be presented at the finish line to random finishers. It is winter, after all! We're not going to ask you to wait around to see if you won something!

*** The scheduled time for the awards presentation may be moved a bit depending on weather and number of athletes still on course

INFORMATION: Most questions are answered right here on the race website. If you have a question that isn't answered here, call Darrin or Jill at 303-642-7917, or shoot us an email at darrin@racingunderground.com



Half-Marathon entry is limited to the first 650 registrations. 5K registration is limited to the first 350 entries. Once a distance has filled, we cannot accept any additional entries for that distance.

Your entry fee includes entry into the race, a finisher's medal (for half-marathon runners who complete the course), FREE race photo downloads, fun music, a racer goody bag, hot cocoa and tasty post-race food, entry into our sponsor merchandise drawing, and if you are one of the speedy guys or gals up front in the half-marathon, you may take home a bit of cash!!!

A long sleeve gender specific tech shirt will be included with all adult entries. Youth 5k entries will include a short sleeve 50/50 t-shirt.

Click button to register
online for Ralston Creek
or the Entire Series!

ENTRY FEES: Ralston Creek 5k or Half