How fast can you drive on streets with no posted speed limit? What Idaho law says
There’s little excuse in downtown Boise to be caught speeding — partly because there are so many traffic lights and congestion gives you little reason to speed, but also because it’s hard to miss the speed limit signs dotted around the city.
If you were curious, the speed limit throughout the downtown area varies from 25 to 35 mph — 35 mph along the busier streets on the south side, such as Front and Myrtle Streets, and 25 mph in downtown proper such as Capitol Boulevard.
But once you leave the Treasure Valley or even enter some neighborhood roads, it can become a little foggier about how fast you can go.
Even when driving on roads in Boise and the rest of the region that don’t have a posted speed limit, there’s still a default speed limit. And failing to drive within the speed limit can result in expensive fines and even criminal charges.
Here’s what to know about speed limits in and around Boise and the penalties for speeding in Idaho:
What’s the default speed limit in Idaho?
In Idaho, state law dictates the speed limit if a specific one isn’t posted when outside of a city’s limits.
Title 49, Chapter 6 of the Idaho Statutes states that if a speed limit is not posted, the limit in any residential, business or urban district is 35 mph.
The same chapter also details that the speed limit on interstate highways is 75 mph under state law and on state highways it is 65 mph unless otherwise posted for both.
Both highway limits may be increased by 5 mph “if the Department (of Transportation) completes an engineering and traffic study on the interstate highway and concludes that the increase is in the public interest and the transportation board concurs with such conclusion.”
But there are exceptions to the state rule. Some cities in the state have their own default speed limits that supersede the state law. In Nampa, public parks and alleys have a speed limit of 15 mph unless otherwise posted while all other city roads are 20 mph, Sergeant Doug Howard of the Nampa Police Department told the Idaho Statesman.
The same speed limits exist in Boise, except alleys — which are considered minor public access ways at the back or side of a property — have a speed limit of 10 mph.
What’s the penalty for speeding in Idaho?
The penalty for speeding in Idaho depends on where you’re driving and how fast you’re going.
According to the website DrivingLaws.org, drivers over the limit between 1 and 15 mph will incur a fine of $90, while 16 mph or more will come with a $155 fine. Speeding over the posted limit in a construction zone will incur an additional fixed penalty of $50 while speeding over the posted limit in a school zone will result in an extra $75 fine.
The Idaho Division of Motor Vehicles may also assess demerit points to the driver’s license; driving over the limit by 1 to 15 mph will result in three points, and 16 mph and over in four points.
The DMV is authorized to suspend the license of a driver who accumulates too many points from 30 days to six months. License points are removed after three years.
This story was originally published October 13, 2022 at 4:00 AM.
