The Idaho Transportation Department says the majority of interstates 15, 84, and 86 will see the increase, which also raises the speed limit for trucks to 70 mph.
ITD says that the urban areas of the interstate, such as the stretch from Caldwell to East Boise, will stay at 65 mph.
The increase in the speed limits was approved by the Idaho Legislature earlier this year.
ITD says since the increase was approved it is been completing the necessary speed studies, engineering reviews, and stockpiling supplies for the signage changeover.
The department says it is still studying speed limit increases for the state highway system as well.
AAA Idaho criticized ITD's decision to increase the speed limits, especially so soon after the increase was approved.
"AAA Idaho expressed concerns regarding the advisability of raising speed limits on interstate and state roads in testimony, news releases and guest opinions during the 2014 legislative session," said spokesman Dave Carlson in a press release. "The concerns focused on the perceived need to raise limits in the first space and the potential traffic safety implications speed limit changes could have on interstate routes and state highways."
Carlson went on to question how quickly ITD performed the required studies before the increase could be put in place.
"AAA is unaware how the state system could have been analyzed so completely in such a short time. AAA is concerned that the rapid switchover itself could pose safety risks for highway users. AAA is also deeply concerned about the process and will look into the matter."
"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."