Colorado speed limits and key traffic laws

By the end of this topic you can

• You can state Colorado's default speed limits for each road type.
• You can explain the basic speed rule and the 75 mph maximum.
• You can describe what happens to fines in school and work zones.
• You can stop correctly for a school bus.
• You can follow the move over law and the left-lane rule.

What you need to know and understand

• No one may drive faster than is reasonable and prudent for conditions, whatever the sign says.
• Unless signs say otherwise: 20 mph on narrow, winding mountain highways and blind curves; 25 mph in business districts; 30 mph in residence districts.
• 40 mph on open mountain highways; 55 mph on other open highways; 65 mph on four-lane interstates, freeways and expressways.
• 75 mph is the absolute maximum on any Colorado highway.
• Fines are doubled for moving violations in posted school zones and for speeding in designated work zones.
• Stop at least 20 feet from a school bus showing flashing red lights.
• On highways of 65 mph or more, do not cruise in the left (passing) lane.

Colorado's default limits

These speeds apply when no sign shows a different limit and no special hazard calls for slower driving. Cities and towns can set their own limits by ordinance, so always read the signs.

• 20 mph: narrow, winding mountain highways and blind curves
• 25 mph: business districts
• 30 mph: residence districts
• 40 mph: open mountain highways
• 55 mph: other open highways
• 65 mph: surfaced four-lane interstates, freeways and expressways
• 75 mph: the highest limit any Colorado road may have

School buses, emergency scenes and work crews

When a school bus stops with its red lights flashing, drivers in both directions must stop at least 20 feet away and wait until the lights go off. The yellow lights come on at least 200 feet before the bus stops, so slow down when you see them. You do not need to stop if the bus is on the other roadway of a highway divided by a median or other clear dividing section.

Colorado's move over law covers stationary emergency vehicles with red, blue or white lights, tow trucks with yellow lights, utility vehicles with amber lights, and any stopped vehicle with hazard lights on. On a road with two or more lanes in your direction, move over so there is a full lane between you and the stopped vehicle. If you cannot move over safely, slow down: 25 mph or less where the limit is under 45 mph, or 20 mph below the limit where it is 45 mph or more.

Speeding fines are doubled in designated maintenance, repair and construction zones, and moving-violation fines are doubled in posted school zones.

Passing and lane use

Pass on the left and do not move back until you are safely clear. Do not pass on hills or curves where you cannot see ahead, or within 100 feet of an intersection or railroad crossing. On highways with a limit of 65 mph or more, use the left lane only to pass or turn left, unless traffic is too heavy to merge right. Our Colorado mountain winter driving guide adds the traction law rules for I-70.

Common mistakes

• Treating the posted limit as a safe speed in snow, ice or fog.
• Passing a stopped school bus on an undivided road because it is on the other side.
• Not moving over for a stopped car with hazard lights; Colorado's law includes them.
• Sitting in the left lane on a 65 or 75 mph highway when not passing.

Test yourself: Colorado speed limits and key traffic laws

Answer each question, then read the explanation. Questions come in a random order each time.

Go deeper

• Colorado Hands-Free Law
• Colorado 30-Hour Driver Ed vs 4-Hour Driver Awareness Course
• Colorado 50-Hour Driving Log and Affidavit of Liability Checklist