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Nathan Jerke
Public Information Specialist
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First interstate speed-limit change in nearly two decades begins July 1

BOISE - Idaho drivers will see the first change to interstate speed limits in nearly two decades beginning July 1 with an increase on most rural stretches of interstate across Southern Idaho, the Idaho Transportation Department announced.

For the majority of interstates 15, 84, and 86, the speed limit will increase to 80 mph for vehicle traffic and 70 mph for trucks. The speed limit in the urban areas of the Treasure Valley, between Caldwell and east Boise, as well as through Pocatello and Idaho Falls, will remain at 65 mph.

State forces will work to implement the speed changes on all sections of interstate throughout the day July 1. Some areas of interstate could be delayed until July 2, depending on the pace of work or other impacts such as weather.

There are no changes to the 65-mph speed limit on Interstate 90 through northern Idaho at this time.

This is the first statewide increase to the interstate speed limit since an increase from 65 to 75 mph in 1996. The speed limit was raised from 55 mph to 65 mph in the 1980s.

The increased speed limit, approved by the Idaho Legislature during the 2014 session (S 1284), increases the maximum speed limits on interstate highways to 80 mph for vehicles and 70 mph for trucks as deemed appropriate by ITD.

The law was signed by Governor C.L. “Butch” Otter on March 18 and becomes effective July 1. The 80-mph speed limit is authorized “if the department completes an engineering and traffic study on the interstate highway and concludes that the increase is in the public interest,” the law reads.

"The new speed limit is appropriate for safety and traffic flow," said ITD Chief Operations Officer Jim Carpenter. “Analysis of crash data, existing speed studies and the rural nature of these sections of highway all factored heavily in making these changes.”

ITD has been preparing for interstate speed-limit changes by completing the necessary speed studies, engineering reviews, and stockpiling supplies for the one-day change.

The revised speed limit law also allowed for speed-limit increases on state highways to 70 mph. Any increases on state highways will be completed at later dates as engineering studies can be completed.

Drivers are reminded that the speed limit does not take effect until the signs are posted on each section of roadway. The 75-mph speed limit signs remain enforceable until replaced. The 80-mph speed limit will be legally enforceable immediately upon posting.

Questions? Visit us online at itd.idaho.gov, follow ITD on Twitter (@IdahoITD) or Facebook and check travel conditions at 511.idaho.gov or dial 5-1-1. Please slow down in highway construction zones and pay attention. Safety for drivers and workers is our highest priority.