MileCheckFrom the Front Range to the western canyons, Colorado's highways run on mile markers — and in the I-70 mountain corridor, the mile marker is how CDOT announces everything from chain laws to closures. Here's how they work, and how to see your exact one plus live conditions in real time.
How Colorado numbers its highways
Colorado's mileposts count up from the west and south state lines. On I-70 that means mile marker 0 at the Utah line, with the numbers climbing east through Grand Junction and Denver to the Kansas line around mile 450. On I-25 the numbers rise from New Mexico north toward Wyoming. State highways are signed CO or SH. Mile marker data for every Colorado highway is bundled into MileCheck and works offline.
The corridors people actually drive
- I-70 crosses roughly 450 miles of the state, from the Utah line through Grand Junction, over the Continental Divide, and through Denver to Kansas.
- I-25 runs the Front Range through Pueblo, Colorado Springs, Denver, and Fort Collins.
- US-50 and US-160 carry traffic across the southern half of the state; US-40 and US-550 — the Million Dollar Highway — thread the high country.
Where mile markers matter most: the I-70 mountain corridor
The stretch of I-70 west of Denver is the classic case for knowing your milepost. The Eisenhower–Johnson Memorial Tunnel sits around mile markers 213 to 215 — at roughly 11,100 feet, the highest point on the entire interstate system. When CDOT activates the chain law or the traction law in winter, the affected stretch is announced by mile marker. So is every closure at Vail Pass or Glenwood Canyon. If you don't know your milepost, you don't know whether the restriction applies to you.
Winter chain and traction laws
Colorado is one of the few states with a codified traction law and chain law for passenger vehicles, and in a storm both can activate on short notice. The mountain corridor between Dotsero and Morrison is where drivers meet them most, and the boundaries are always given in mile markers. Getting the alert before you commit to the climb — instead of at the checkpoint — is the difference between an easy pull-off and a long wait in the snow.
Live CDOT alerts, in one place
MileCheck pulls live road alerts straight from CDOT and COtrip: closures, crashes, road conditions, and chain restrictions, tied to the mile marker and direction so you can see what's ahead of you on your route. Whether it's a rockfall closure in Glenwood Canyon or a traction law over Vail Pass, the alert shows up where it applies.
Everyday and emergency
Whether you're watching the chain law status in a February storm, reporting a breakdown on the eastern plains, or just telling a friend where to meet you, the mile marker is the location Colorado's roads run on. MileCheck shows yours in real time, down to a tenth of a mile, even where the cell signal drops.
Keep reading
Nearby state guides: Kansas · Nebraska · New Mexico · Oklahoma · Utah · Wyoming
Essentials: What to tell 911 on the highway · How to find your mile marker · Browse the live mile marker map · All 50 states