Running Races in Thornton, Colorado 2026 | Browse All Races

There are 7 running races in Thornton, Colorado in 2026. The next is the RMRR Fall Marathon Training Series #2 on September 13. Distances include 5K races, 10K races, half marathons.

RMRR Fall Marathon Training Series #2

Sun, Sep 13 · Thornton, CO Thornton

Road RMRR Fall Marathon Training Series #2 - 20kmRMRR Fall Marathon Training Series #2 - 30km

From $20 Open Closing Soon

RMRR September 5k/10k

Sun, Sep 13 · Thornton, CO Thornton

Road 5k10k

From $10 Open Closing Soon

RMRR Fall Marathon Training Series #3

Sun, Sep 27 · Thornton, CO Thornton

Road RMRR Fall Marathon Training Series #3 - 10 MileRMRR Fall Marathon Training Series #3 - 20 Mile

From $20 Open

I Can 5k

Sat, Oct 3 · Thornton, CO Thornton

Open

I Ain't Scared (of 5k)

Sat, Oct 31 · Thornton, CO Thornton

Road 5k

From $29 Open

WinterFest 5k & Fun Run

Sat, Dec 12 · Thornton, CO Thornton

Road 5k Run/Walk -TIMED and ScoredFun Run/Walk (Untimed, approx .75 miles)

From $12 Open

Unicorn 5k (North)

Sat, Jun 19 · Thornton, CO Thornton

Road 1/2 (ish) Mile Saunter - untimed1/2 (ish) Mile Saunter - untimed5k Run/Walk +1

From $16 Open

Running Races in Thornton, Colorado — 2026