The Idaho Transportation Department has begun the planning process to improve the South Blackfoot Interchange at Exit 89. The South Blackfoot Interchange has served motorists since 1961. Since then, eastern Idaho’s population and traffic volumes have greatly increased.
At this interchange, Interstate 15 crosses over U.S. Highway 91 on the Fort Hall Reservation. The interchange is in an area of I-15 that is heavily used for commercial, residential and recreational travel. To improve safety and mobility for motorists, it is necessary for ITD to replace the interchange with a design that has increased capacity and meets current standards.
Project plans currently include:
- Lengthening ramps to improve safety.
- Adding a dedicated exit lane to off-ramps to improve ramp operations.
- Adjusting the interchange to accommodate future additional lanes on I-15.
Improvements to this interchange will be developed and designed based on traffic and other technical data, an environmental evaluation, surveying, and input from the public. The planning, design and environmental evaluation stage of the project is expected to be completed in 2026. Construction of the improvements is anticipated to begin in 2030, depending on the availability of further funding. This project is utilizing both state and federal funding.
ITD will provide multiple opportunities for the public to learn more about the I-15 South Blackfoot Interchange project throughout project development, including a public open house and pop-up meetings in early 2025. For more information visit the project website at itdprojects.idaho.gov/pages/i-15-corridor or call 208-252-5553.