Car speed limits in Idaho (2026)
Last reviewed: 9 October 2026
In short: Unless otherwise posted, maximum speeds are 35 mph in residential, business or urban districts, 55 mph in other locations, 65 mph on state highways and 75 mph on interstate highways; there is no separate figure for divided highways. Some limits can be raised after an engineering and traffic study. In school zones the posted limit applies, with a minimum penalty of $75.
| Rule | What applies |
|---|---|
| Built-up areasPassenger car on public roads | 35 mph [1] |
| Outside built-up areas (single carriageway)Passenger car on public roads | 65 mph on state highways; 55 mph in other locations [1] |
| MotorwaysPassenger car on public roads | 75 mph on interstate highways [1] |
| Outside built-up areas (dual carriageway or expressway)Passenger car on public roads | 65 mph on state highways and 75 mph on interstate highways (no separate figure for divided highways) [1] |
| Residential streetsPassenger car on public roads | 35 mph in any residential district, unless otherwise posted. [1] |
| School zonesPassenger car on public roads | The posted school-zone limit applies; there is no statutory figure. Where the sign says 'when children are present', one or more children present within the marked zone is enough. Minimum penalty $75. [2] |
Notes
- State highway limits may be raised to 70 mph after a department study with transportation board concurrence. Other locations may be posted up to 70 mph.
- The limit may be raised to 80 mph on an interstate after an engineering and traffic study and with transportation board concurrence.
- The state highway limit may be raised to 70 mph, and the interstate limit to 80 mph, after an engineering and traffic study with transportation board concurrence.
Sources
- Idaho Legislature: Section 49-654 - Basic rule and maximum speed limits (Idaho Statutes, Title 49, Chapter 6; Internet Archive snapshot of 11 December 2025) (consulted 9 October 2026) · all sources
- Idaho State Legislature: Section 49-658 School zone speed limit — Penalty (Idaho Statutes, Title 49, Chapter 6; Internet Archive snapshot of 5 June 2026) (consulted 10 October 2026) · all sources
Idaho and neighbouring states
| State | Built-up areas | Outside built-up areas (single carriageway) | Outside built-up areas (dual carriageway or expressway) | Motorways |
|---|---|---|---|---|
| Idaho | 35 mph | 65 mph state hwys; 55 mph other | 65 mph state hwys; 75 mph interstates | 75 mph (interstates) |
| Montana | 25 mph | 70 mph day / 65 night | 75 mph day / 70 night | 80 mph (65 in urban areas) |
| Nevada | Posted limit; 80 mph cap | Posted limit; 80 mph cap | Posted limit; 80 mph cap | 80 mph maximum |
| Oregon | 20 mph business; 25 mph residential | 55 mph; 65 mph on listed highways | — | 65 mph; 70 mph on parts of I-84, I-82 |
| Utah | 25 mph | 55 mph | — | Posted, up to 75 mph |
| Washington | 25 mph | 50 mph county; 60 mph state | — | 60 mph; up to 75 mph where posted |
| Wyoming | 30 mph | 70 mph state highways; 65 mph other paved | — | 75 mph; 80 mph where designated |
More rules in Idaho
- CannabisPossession for personal use: Illegal; penalties under the Controlled Substances Act · Growing at home: No (illegal to manufacture)
- Minimum age for a car driving licenceMinimum age for a car licence: 15 (daylight only); full privileges at 16 · Earliest age to drive a car supervised: 14½ (driver training permit)
- E-bikes and speed pedelecsLegal class: Class 1-3, bicycle rules
- FireworksConsumers may buy and use category F2 fireworks: Yes (non-aerial only, set dates)
- Knives and pepper sprayFolding pocket knives: Blade 6 in or less is not a 'deadly weapon' · Locking or one-handed knives: No separate rule; 6 in blade limit
- Statutory minimum wageNational statutory minimum wage: Yes · Current adult minimum wage (gross): $7.25 per hour
- Using a mobile phone while drivingHolding a phone while driving banned: Banned (hands-free allowed)
- Seat belts and child seatsSeat belt compulsory in front seats: Yes, all seats · Seat belt compulsory in rear seats: Yes, all seats
- Tobacco and nicotine age limitsMinimum age to buy tobacco: 21 · Minimum age to buy e-cigarettes: 21
- Drink-driving limitsBlood alcohol limit for ordinary drivers: 0.08% · Lower limit for novice or young drivers: 0.02% (under 21)
Related pages
General information, not legal advice. Rules change: check the official source before you fly or ride.