Colorado Driving Laws 2026: Speed Limits, DUI BAC Limits and Road Rules for the Written Test

What are the legal speed limits in Colorado when no sign is posted? Colorado sets 25 mph in urban areas, 40 mph on open mountain highways, and 75 mph on rural interstates. The DMV knowledge test is 25 questions with a 80% pass requirement. Colorado DUI: 0.08% is per se DUI; a BAC between 0.05% and 0.07% is DWAI (Driving While Ability Impaired) and also a criminal offense, a unique distinction most states do not have. Headlights are required 30 minutes after sunset and in precipitation.

1. Speed Limits in Colorado

Colorado sets speed limits by zone and road type, and mountain highways get their own tiers. On narrow, winding roads through the Rockies, 20 mph is the default. On rural interstates, it goes up to 75. Heres the full statutory breakdown when no sign is posted:

Key test point: Colorados mountain roads are unforgiving, even if you are at the posted limit, black ice, sudden snowfall, or reduced visibility on a blind curve requires immediate speed reduction. Work zones also carry reduced posted limits that are strictly enforced. Driving slower than the minimum posted speed is also a traffic violation.

2. Right-of-Way: Who Goes First

Colorados knowledge test hits right-of-way hard, especially yield-to-uphill rules on mountain roads and pedestrian crossings. Remember: right-of-way is always yielded, never claimed.

4-way stop (all arrive at once)

Driver to the right

4-way stop (one arrives first)

Driver who arrived first

Roundabout / traffic circle

Vehicles already inside the circle

Emergency vehicles (lights/siren)

Emergency vehicle, pull to the right and stop

Pedestrians in crosswalk

Pedestrians always

T-intersection (no signs)

Through road traffic; drivers on the dead-end must yield

Yield sign

Cross traffic and pedestrians always

Merging onto a highway

Traffic already on the highway

3. Turns & Signal Laws

Colorado requires 100 feet of continuous signaling in urban areas and 200 feet on four-lane highways over 40 mph. Right turns on red are generally allowed after a full stop. Heres how every turn scenario breaks down under Colorado law:

Right turn on red

Permitted after a full stop unless a sign prohibits it. Yield to pedestrians and cross traffic.

No right turn on red

When posted, you must wait for a green light before turning right.

Left turn on red

Only allowed from a one-way street onto another one-way street, after a full stop.

Left turn from two-way street

Start from the left lane; end in the left lane of the cross street.

Right turn

Stay as close to the right curb as possible; end in the right lane.

U-turns

Legal where not prohibited by a sign; must not interfere with traffic. Illegal in business districts in Colorado unless at a designated intersection; also illegal on divided highways, in front of fire stations, and anywhere visibility is insufficient.

4. Lane Rules & Line Markings

On Colorados mountain corridors, lane discipline is critical, passing on a blind curve is illegal and potentially fatal. On urban freeways through Denver and Colorado Springs, center turn lane and carpool rules apply. Heres the complete breakdown tested on the Colorado DMV exam:

Center turn lane (CTSL)

Used only to begin or complete a left turn; not for through travel or merging. You may travel no more than 300 feet in the CTSL.

Solid white line

Do not cross; marks the edge of the road or a lane that should not be changed.

Solid yellow line (your side)

No passing allowed.

Broken yellow line

Passing allowed when safe.

Solid + Broken yellow centerline

Passing allowed only on the broken-line side.

5. Passing Another Vehicle

On two-lane mountain highways through the Rockies, passing is one of the most dangerous decisions a driver makes. Colorado law sets firm rules on when and where it is illegal, and the consequences of getting it wrong at altitude are severe:

• Only pass on the left, using the oncoming lane, when it is safe and legal.
• Do not pass within 100 feet of an intersection, railroad crossing, bridge, or curve where your view is limited. Look for the No Passing Zone pennant sign.
• The vehicle being passed must not speed up while you are overtaking.
• Return to your lane before coming within 200 feet of oncoming traffic. When you can see both headlights of the vehicle you passed in your rearview mirror, it is safe to return to your lane.
• Never pass a stopped school bus with flashing red lights, this applies in both directions on undivided roads.
• You may pass on the right only when the vehicle ahead is turning left and there is a usable lane to the right.

6. Following Distance

On Colorados mountain highways, stopping distances are dramatically longer, a car at 55 mph takes about 200 feet to stop under normal conditions, and far more on ice or wet roads. The 3-second rule is your floor under ideal conditions. In the mountains, double it.

7. School Buses & Emergency Vehicles

Colorado law requires you to stop at least 20 feet from a school bus when its red lights are flashing. This is directly tested on the Colorado knowledge exam, know the distance, know the exceptions.

School Buses

• When a school bus stops with flashing red lights and an extended stop arm, all traffic in both directions must stop on undivided roads.
• On roads with a true median or physical barrier, only traffic behind the bus must stop, oncoming traffic may proceed.
• A center turn lane does not count as a divider. On 4+ lane roads without a raised median or barrier, all directions must stop.
• You must remain stopped until the red lights stop flashing and the stop arm is retracted.
• Colorado requires stopping at least 20 feet from the front or rear of a stopped school bus with flashing red lights. Violation can result in significant fines and points on your license.
• Railroad crossings: School buses must stop at ALL railroad crossings, with or without passengers, even if no lights are flashing and no train is visible. This is a frequently tested rule.

Emergency Vehicles

• When you see or hear an emergency vehicle (police, fire, ambulance) with lights or siren: pull to the right edge of the road and stop. Do not block intersections.
• Move Over Law (Colorado): When approaching a stopped emergency vehicle, law enforcement, tow truck, or highway maintenance vehicle with lights flashing on a multi-lane road, move one lane away when safe. If changing lanes is not possible, slow to a speed that is safe for conditions.

8. DUI & DWAI: Two Impairment Tiers

Colorado is one of the few states with two distinct impaired-driving offenses, DWAI starts at 0.05% BAC (impaired to the slightest degree) and DUI kicks in at 0.08% (substantially incapable of safe driving). Marijuana DUI is enforced on the same standard. Refusing a chemical test costs you a 1-year revocation plus a mandatory 2-year ignition interlock.

9. Seat Belts & Child Seats

Colorado requires seat belts for the driver, all front-seat passengers, and all children under 16. The child passenger protection law sets specific restraint requirements by age and weight, the driver is responsible if a parent is not in the vehicle.

10. Where You Cannot Park

Colorados parking rules include a combined distance rule, 30 feet from a stop sign, signal, or railroad crossing, and 15 feet from a fire hydrant. Bikes lanes are also off-limits. Know every prohibition for the Colorado DMV test:

• Within 15 feet of a fire hydrant
• Within 20 feet of a crosswalk at an intersection
• Within 30 feet of a stop sign, yield sign, or traffic signal
• Within 50 feet of a railroad crossing
• On a sidewalk, in front of a driveway, or on a bridge
• In a no-parking zone or alongside a curb painted yellow or red
• Double parking (alongside a vehicle already parked at the curb)
• Headed downhill: turn wheels toward the curb. Headed uphill with a curb: turn wheels away from curb. Uphill without a curb: turn wheels toward the shoulder.

11. Driving in Bad Weather

Colorados weather is legendary for its unpredictability, blue skies can turn into a whiteout blizzard on a mountain pass within minutes. Black ice forms on shaded canyon roads even when it is sunny nearby. Heres what the Colorado Driver Handbook says about handling it:

• Headlights required from sunset to sunrise or whenever visibility is less than 1,000 feet. In fog, use low beams, high beams reflect off fog and cut visibility further.
• In heavy fog, use low beams, high beams reflect off fog and reduce visibility.
• If you start to hydroplane, ease off the gas gently. Do not brake hard or turn sharply.
• In icy conditions, brake gently well in advance. Start slowing earlier than normal. Leave extra following distance.
• If your car goes into a skid, steer in the direction you want the front of the car to go. Do not overcorrect.
• Never use cruise control on wet, icy, or slippery roads.

12. Points & License Suspensions

Colorado tracks every moving violation on your record. Accumulate too many points and your license is suspended, no exceptions. DWAI and DUI carry the highest point values. Heres how Colorados point system works:

Note: Colorados DMV can also require re-examination if your driving record shows a pattern of violations. Losing your license in Colorados mountain communities, where driving is often the only transport option, is a serious consequence.

13. Headlight Rules

Colorados wide-open rural highways and mountain roads demand good headlight discipline. The law specifies exactly when to switch to low beams, 500 feet oncoming, 200 feet following. That following distance difference from other states is a common test error.

Key test point: Colorados rule is 500 feet for oncoming and 200 feet for following, not 300. This distinction from other states is a frequent source of wrong answers on the Colorado DMV knowledge test.

14. Night Driving

Driving at night in Colorado is a different challenge than in most states. Mountain passes, unlit canyon roads, and elk crossing highways at dusk create hazards that flat-state drivers never face. The Colorado handbook calls out dawn and dusk specifically as more hazardous than daytime driving.

15. Cell Phones & Distracted Driving

Colorado enacted a statewide ban on handheld mobile device use while driving. Any use of a handheld device, calls, texting, scrolling, is prohibited. On mountain roads where a momentary distraction can send you off a cliff, the stakes are higher than anywhere else.

Key test point: Colorados handheld ban applies to all drivers at all times while in motion, not just texting. A second offense also adds 4 points to your record. On mountain roads, distracted driving is not just illegal, it is lethal.

16. Railroad Crossings

Colorados rail lines cross highways throughout the Front Range and mountain corridors. The knowledge test expects you to know exactly how far back to stop and which vehicles must always stop at crossings, regardless of signals.

Key test point: Never drive around or under a lowered crossing gate, it is illegal and extremely dangerous. Wait until gates are fully raised and all tracks are clear.

17. How to Drive a Roundabout

Roundabouts are common at Colorado intersections from Denver suburbs to mountain resort towns like Breckenridge and Vail. The Colorado DMV tests them directly. The rule that trips everyone up: you always yield when entering, regardless of what the driver inside is doing.

Key test point: The most common wrong answer on roundabout questions is thinking you have right-of-way when entering. You never do, yield to traffic already inside.