Iowa Driving Laws 2026: Speed Limits, OWI BAC Limits and Iowa DOT Road Rules for the Permit Test

What are the default speed limits in Iowa when no sign is posted? Iowa sets 20 mph in business districts, 25 mph in residential or school districts, 45 mph in suburban districts, and a 60 mph general default when no other restriction applies, effective July 1, 2026. Iowa calls drunk driving OWI, Operating While Intoxicated, not DUI. The OWI threshold is 0.08% for adults, while drivers under 21 face license sanctions at a BAC of 0.02% or more. Headlights are required from sunset to sunrise and whenever conditions make persons or vehicles not clearly discernible at 500 feet. Iowa also prohibits handheld electronic-device use while driving under its hands-free law.

1. Speed Limits in Iowa

Iowa sets speed limits by zone type and road classification, and the suburban district designation (45 mph) is unique among Midwestern states. The posted limit is the fastest you can legally drive under ideal conditions; conditions require you to go slower. Heres the full statutory breakdown:

Key test point: Iowas handbook puts it plainly: stopping at 60 mph takes over three times the distance it takes at 30 mph. The posted limit is the fastest you can legally drive under ideal conditions, when conditions are not ideal, you must slow down regardless of what the sign says. Iowas 20 mph business district limit is notably lower than most states 25-30 mph defaults.

2. Right-of-Way: Who Goes First

The Iowa knowledge test covers right-of-way scenarios at intersections with no signs, when entering from private roads, and when yielding to pedestrians. Right-of-way is always yielded, never seized.

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

Iowas signal distance requirement depends on the speed limit: at least 100 feet if the limit is 45 mph or less; at least 300 feet if faster than 45 mph. The handbook also recommends signaling at least 3 seconds early. Right turns on red are permitted after a full stop unless a sign prohibits it:

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 and safe. On a curve or near the crest of a grade or hill, you may not turn to proceed in the opposite direction if your vehicle cannot be seen by approaching drivers from either direction within 500 feet.

4. Lane Rules & Line Markings

On Iowas interstate road system, vehicles incapable of attaining and maintaining 40 mph are prohibited, and lane discipline keeps traffic flowing safely. On rural two-lane roads, knowing when the center line allows passing versus prohibits it is critical. Heres the full breakdown tested on the Iowa DOT exam:

Center turn lane (CTSL)

Used only to begin or complete a left turn; not for through travel or merging.

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 Iowas straight, flat county roads, passing looks easy, until you misjudge closing speed. The Iowa handbook specifies that when you have passed a vehicle, you must check that you can see its headlights in your rearview mirror before returning, then signal a right turn before merging back:

• Only pass on the left, using the oncoming lane, when it is safe and legal.
• Do not pass on the left within 100 feet of or while traversing an intersection or railroad crossing, or within 100 feet of a narrow bridge, viaduct, or tunnel when signs prohibit passing. Do not pass where a hill or curve prevents a clear view for a sufficient distance. Look for the No Passing Zone pennant sign.
• The vehicle being passed must not speed up while you are overtaking.
• When passing on the left, return to the right side before coming within 300 feet of an oncoming vehicle on roads with a speed limit over 30 mph, or within 100 feet when the speed limit is 30 mph or less. Only return after you can see the vehicle you passed in your rearview mirror, then signal before moving back to the right lane.
• Never pass a stopped school bus with flashing red lights, this applies in both directions on undivided roads.
• Passing on the right is allowed only where Iowa law permits, including when the vehicle ahead is making or about to make a left turn and there is sufficient unobstructed roadway width, or on a roadway with four or more lanes of moving traffic. Do not pass by driving off the pavement or onto the shoulder.
• Passing bicycles: Iowa DOT requires drivers to completely change lanes when passing a bicyclist, giving the bicyclist the entire lane, and not return to the right until the bicyclist is visible in the rearview mirror.

6. Following Distance

Iowas handbook uses the 3- to 4-second rule in normal traffic and good weather. At 40 mph it recommends 4 to 5 seconds, and when roads are slippery or the vehicle ahead blocks your view, 6 or more seconds:

7. School Buses & Emergency Vehicles

Iowas school bus stop law is directly tested on the knowledge exam, including the exact 15-foot minimum stop distance when approaching from behind. On a two- or three-lane road, traffic meeting a stopped school bus from the front must also stop; on a road with two or more lanes in each direction, opposite-direction traffic does not stop.

School Buses

• When a school bus stops with flashing red lights and an extended stop arm on a two- or three-lane road, traffic approaching from both directions must stop.
• On a road with two or more lanes in each direction, traffic approaching from behind the bus must stop, but opposite-direction traffic does not need to stop.
• A center turn lane does not change the rule. Two- and three-lane roads require traffic from both directions to stop; roads with two or more lanes in each direction do not require opposite-direction traffic to stop.
• Approaching from behind, stop no closer than 15 feet from the rear of the bus and remain stopped until the stop arm is retracted and the bus starts moving again.
• Meeting the bus from the front on a two- or three-lane road, slow to no more than 20 mph when amber lights flash, then stop when the stop arm is extended and remain stopped until it is retracted.
• Railroad crossings: School buses are among the vehicles that generally must stop 15 to 50 feet before railroad tracks; exceptions apply when directed by a police officer or traffic-control signal or when the crossing is officially marked exempt.

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 (Iowa): Change lanes or slow down when approaching a stationary emergency vehicle, tow/recovery vehicle, maintenance/construction vehicle, solid-waste or recycling vehicle with flashing lights, or any stationary motor vehicle displaying hazard lights. If changing lanes is not possible or safe, slow to a reasonable speed and be prepared to stop.

8. OWI Laws & BAC Limits

Iowas impaired driving offense is called OWI, Operating While Intoxicated. Iowa defines OWI to include a BAC of 0.08% or higher or operating with a controlled substance in the system. Drivers under 21 with a BAC of 0.02% or more face a minimum 60-day revocation; a BAC of 0.08% or more carries a minimum 180-day revocation.

9. Seat Belts & Child Seats

Iowa requires all front-seat occupants to wear seat belts, and the Child Restraint Law covers every seating position in the vehicle for children from infancy through age 17. The handbook is direct: seat belts reduce your chance of serious injury or death in a front-seat crash by at least 50 percent.

10. Where You Cannot Park

Iowas parking rules include some distances you will not find in most other states, 5 feet from a fire hydrant (not 15), 10 feet from a stop sign, and 50 feet from railroad crossings. Know every number for the Iowa DOT exam:

• Within 5 feet of a fire hydrant
• When legally parking at a curb, park within 18 inches of the curb
• On a crosswalk
• Within 10 feet of a stop sign
• Within 20 feet of a fire station entrance
• Within 50 feet of a railroad crossing
• On a sidewalk, in front of a driveway, on any bridge outside city limits, or in highway tunnels
• In a posted no-parking zone or where yellow curb or pavement markings prohibit parking
• 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

Iowas weather extremes test drivers year-round, spring flooding closes river-bottom roads, fog in river valleys along the Des Moines and Iowa Rivers reduces visibility to near zero, and winter brings ground blizzards on open farmland that make roads invisible in seconds. The handbook covers all of it:

• Headlights required in Iowa from sunset to sunrise or whenever conditions make persons or vehicles not clearly discernible at 500 feet. In fog, use low beams, high beams reflect back off water droplets and reduce visibility.
• 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

Iowas point system is used for the habitual offender provisions involving specified serious convictions; ordinary moving violations do not use the generic 3-, 4-, 5-, or 8-point values used in some other states. Separately, three or more countable moving violations committed within 12 months can trigger habitual-violator action, and six moving violations within two years can result in a one-year habitual-offender bar.

Key test point: Iowa also has a Driver Improvement Program. Eligible drivers may be assigned the program instead of immediate suspension after three countable moving violations within 12 months, speeding 25-29 mph over the limit, or a first offense of unlawfully passing a school bus.

13. Headlights: Iowas 1,000-Foot Rule

Iowas headlight dimming distances are unlike almost every other state in the country, 1,000 feet for oncoming traffic and 400 feet when following another vehicle. Most test-takers expect 500/300, Iowas numbers are double the typical. Know these before your exam.

Key test point: Iowas dimming distances are 1,000 feet for oncoming vehicles and 400 feet when following, nearly double what most other states require. This is one of the most distinctive rules in Iowas handbook and appears regularly on the DOT knowledge test. Do not confuse Iowas distances with other states 500/300-foot rules.

14. Night Driving

Iowas handbook dedicates specific attention to "overdriving headlights", driving so fast that your stopping distance exceeds what your headlights illuminate. On Iowas long, straight rural roads at night, it is easy to drive faster than your headlights can protect you. Iowa also has one of the highest deer-vehicle collision rates in the Midwest.

15. Cell Phones & Distracted Driving

Iowa prohibits use of handheld electronic devices while driving, including texting, browsing, and calls. Drivers under age 18 with an instruction permit, intermediate license, or special minor restricted license have an additional restriction on making or receiving phone calls while driving. Iowas handbook notes that driver distractions are a leading cause of crashes statewide.

Key test point: Iowas handheld device ban applies to all drivers for all uses, not just texting. Drivers under age 18 with an instruction permit, intermediate license, or special minor restricted license have the additional phone-call restriction described above. Distractions cause a significant share of Iowas crashes annually.

16. Railroad Crossings

Iowas extensive rail network, including BNSF and Union Pacific freight lines and the Iowa Interstate Railroad, crosses public roads throughout the state. The DOT knowledge test covers the 15-to-50-foot stop range, and the fact that you must stop within that range, not just somewhere before the tracks.

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

Iowa DOT has been installing roundabouts at rural intersections and suburban interchanges across the state, replacing dangerous stop-sign intersections with modern traffic circles. The DOT tests roundabout rules directly. The one rule that trips everyone: entering traffic must yield to vehicles already circulating inside, always.

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.