Projects

I-15 South Blackfoot Interchange (Exit 89)

The new interchange design will prioritize safety, operations and capacity to meet eastern Idaho’s growing transportation needs. The design of this interchange is anticipated to be completed in 2026.

I-15 South Blackfoot Interchange (Exit 89)

The new interchange design will prioritize safety, operations and capacity to meet eastern Idaho’s growing transportation needs. The design of this interchange is anticipated to be completed in 2026.

Overview

This project will:

  • Replace the I-15 South Blackfoot Interchange.
  • Improve on- and off-ramps.
  • Make improvements to accommodate additional lanes on the interstate.

Improvements are being designed using an environmental evaluation, traffic and other technical data, surveying and public input.

Map of Exit 89 project area.
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We’re back with another I-15 update!

Are you curious about what’s being planned for I-15 between Fort Hall and Blackfoot? Check out the fall update video to learn about the status of three design projects:

  • I-15 South Blackfoot Interchange (Exit 89)
  • I-15 Exit 89 to Exit 93 Widening
  • I-15 US-26/Blackfoot Interchange (Exit 93)
Drone shot of Exit 89 facing north

Background

The I-15 South Blackfoot Interchange has served motorists since 1961. Since then, eastern Idaho’s population and traffic volumes have greatly increased and interchange design standards have changed.

For these reasons, it necessary to develop a design that will increase capacity and mobility, improve safety and update the interchange to meet current design standards.

Anticipated growth

Eastern Idaho’s traffic volumes have greatly increased since the construction of the South Blackfoot Interchange, and growth is expected to continue. The Average Daily Traffic (ADT) count at this interchange is expected to almost double by 2051. The project team’s goal is to design an interchange that will serve the growing needs of eastern Idaho for years to come.

2023 – 27,500 ADT

2051 – 53,230 ADT

Drone shot of Exit 89 with traffic on I-15.
Roll plot of the recommended design for Exit 89.

Recommended design

The recommended design option for the I-15 South Blackfoot Interchange features:

  • An overpass connected to US-91 on the east side of the interchange.
  • Lengthened interchange ramps, including a 4-foot buffer between mainline I-15 and ramp traffic.
  • Three lanes in each direction on I-15.

Click the image on the left to view a PDF of the recommended design.

Public feedback

ITD hosted two public open houses in 2025 about three projects along I-15 between Fort Hall and Blackfoot: 

Drone shot of the I-15 South Blackfoot Interchange (Exit 89)
  • I-15 South Blackfoot Interchange (Exit 89) 
  • I-15 Exit 89 to Exit 93 Widening 
  • I-15 US-26/Blackfoot Interchange (Exit 93) 

Over 300 people participated in the open houses. The community expressed support for the I-15 South Blackfoot Interchange (Exit 89) project, sharing that plans to improve the interchange ramps will likely improve safety on I-15. Participants approved of the recommended design option and hoped that work would begin as soon as possible.

  • 2024

    Gathered technical information to help develop preliminary design plans

  • 2024-2025

    Developed preliminary design plans

  • 2025-2027

    Develop final design plans

  • TBD

    Construction is dependent on TECM bond funding. Work may begin as early as 2028, depending on the availability of funding.

Frequently Asked Questions

Stay informed & provide input

To remain informed about upcoming opportunities, learn more and to provide feedback:

Downloads & Resources