The Idaho Transportation Department is hosting an open house next week to share proposed improvements to U.S. Highway 20 from Idaho Falls to Arco.
US-20 is one of the few highways that run east to west across the entire United States. This section is a vital route for commerce and the 6,000 eastern Idahoans who work at the Idaho National Laboratory.
Originally built in 1950, the roadway requires robust improvements to continue to serve motorists for years to come. The design proposes increasing safety by adding capacity, widening the road to two lanes in each direction starting at Idaho Falls and moving west. Widening will improve safety for freight, agricultural, recreational and commuter traffic where limited passing opportunities and lines of sight now exist.
Those attending the open house will have the chance to comment on these proposed designs, learn the project timelines and see how construction impacts are being mitigated.
Open house details:
Snake River Event Center at the Shilo Inn
780 Lindsay Blvd, Idaho Falls
Thursday, September 4
4:30 p.m. – 6:30 p.m.
For those unable to attend, an online option will be available September 4-18 at us20arcotoif.com.
“We know this route needs improvements and have been very focused on working towards them,” ITD District Engineer Jason Minzghor said. “We’re excited to get public input on the design and see construction happen in the very near future.”
Construction could begin as early as next summer due to additional funds dedicated to the Transportation Expansion and Congestion Mitigation program by Governor Little and the Idaho Legislature earlier this year. This bonding program enhances safety, improves mobility, further strengthens Idaho’s economy and positively impacts communities across the state for years to come.
Beginning early this week, traffic on U.S. Highway 20 will be routed onto the newly built overpass bridge at South St. Anthony Exit 344. This marks the final stages of construction on a new full interchange at this location.
North and southbound motorists were previously routed onto the ramps while the overpass bridge was being constructed, with speed limits lowered to 35 mph. Traffic will now move to travel on mainline US-20 at a reduced work zone speed.
With this traffic shift, South St. Anthony ramps will be closed as work continues on 400 North under US-20. Workers and equipment will still be present on site, so drivers are urged to stay aware and be cautious.
This project is expected to be substantially complete later this summer, with the ramps and turning movements onto 400 North open then.
Funding for this project is assisted by Governor Little’s Leading Idaho Transportation Expansion and Congestion Mitigation (TECM) fund. The Leading Idaho initiative allows ITD to take a deliberate approach to invest in projects in corridors that will enhance safety, improve mobility, further strengthen Idaho’s economy, and positively impact communities across the state for years to come.
Updates on this project and others across Idaho can always be seen on the Idaho 511 app, or at 511.idaho.gov.
The Idaho Transportation Department is partnering with the Idaho National Laboratory to alert motorists of changes to their commute beginning next week.
Starting Monday, paving operations within the INL site will limit usual turning movements at the Puzzle, the junction of US-20, US-26 and INL. During morning and overnight hours, traffic will be able to make right turns only off US-20 into the site.
From 4 to 6:30 p.m. traffic at the Puzzle will be restricted to outbound only movement, with no inbound turns allowed.
Speed will be reduced to 50 mph on US-20 near and through the Puzzle while this work is completed.
Both inbound and outbound site traffic will be able to access US-20 from an alternative route at West Portland Avenue, Gate Three, one mile west of the Puzzle. No dedicated turning lane exists on US-20 at this intersection, so motorists are urged to be alert and slow down.
Flaggers will be present as needed when INL paving work is near the intersections of US-20 or US-26. Traffic control signs and lower speed limits will not be in effect when work is not actively ongoing along these roadways.
INL paving operations are expected to be complete and traffic running as usual by late September.
INL employees should refer to internal communication regarding effects to their commute on roads within the site. Effects to US-20 and US-26 will be noted on the Idaho 511 app and at 511.idaho.gov.
Traffic will be affected as the Idaho Transportation Department and contractor partners conduct inlaid striping operations on State Highway 33, U.S. Highway 20, and Interstate 15 Business Loop over the next two weeks.
Beginning today, lane closures will be in effect where work is currently underway on SH-33 between Sage Junction and Rexburg. Four miles at one time will be reduced to one lane, with flaggers and pilot cars directing traffic through the work area. Motorists should watch for reduced speed, large equipment and signs indicating construction ahead.
Roadways will be worked on in this order, with all operations expected to be completed by August 15:
- SH-33 between Sage Junction and Rexburg, milepost 59 to 78.
- US-20 west of Idaho Falls, milepost 301 to 307, beginning next week.
- I-15 Business Loop in Idaho Falls (Sunnyside Road from I-15 to Yellowstone Road).
- I-15 Business Loop in Idaho Falls (Yellowstone Road from Sunnyside to Broadway).
Operations on SH-33 and US-20 are being conducted during daytime hours. Crews will work through the night on the I-15 Business Loop in Idaho Falls.
A pilot car and flaggers will only be present on SH-33 this week. Traffic will be directed into one lane and continue to move around the work area on US-20 and I-15 Business Loop.
Inlaid striping is relatively unique in Idaho. The operation involves grinding into the pavement very slightly, creating recessed notches that paint is then applied within. This method aims to extend the life and reflectivity of pavement markings.
Updates regarding these efforts and all roadwork in Idaho can always be found on the Idaho 511 app, or at 511.idaho.gov.
Work to improve and repair the Macks Inn Bridge on US-20 through Island Park will begin on Monday. Crews are customizing handrails, repairing guardrails and installing concrete railings to improve safety for multiple uses in this popular location. These efforts are expected to be completed by Thursday of next week. If needed, finishing work will resume the week following but will not be in effect through the weekend.
One lane of traffic will remain open in each direction throughout this project, with the lane nearest the bridge closed one side at a time. Turning movements to and from businesses and river access will be monitored and allowed to be made as normal.
Drivers can expect to see large equipment on site to correctly locate a sewer line near the bridge. Travelers and recreationists are urged to observe lower speed limits and stay engaged while driving. Be aware of workers and equipment very near open travel lanes.
Updates for this project and others across Idaho can always be seen on the Idaho 511 app, or at 511.idaho.gov.
Today at its regular monthly meeting the Idaho Transportation Board accepted staff recommendations on priority corridors across Idaho using TECM funds to address congestion, including several projects on U.S. Highway 20 near Idaho Falls. Since Transportation Expansion and Congestion Mitigation funds were first used by the department for bonding and advancing major projects in 2022, ITD has delivered timely construction of expansion projects across the state. Today’s actions are a continuation of that.
Funding came from House Bill 25, which was passed by the Idaho Legislature earlier this year. The legislation provides an additional $20 million a year to the Transportation Expansion and Congestion Mitigation fund for the next three years and allows the department to invest an extra $1 billion in the Idaho transportation system.
With this new funding, the following projects have been recommended for further design and construction:
- US-20 west of Idaho Falls: This project will increase capacity by widening the road to two lanes in each direction starting at Idaho Falls and moving west as funding allows. Widening will increase safety for freight, recreational and commuter traffic due to limited passing opportunities and lines of sight. Construction is anticipated start in 2026, two years earlier than planned.
- US-20 widening from Chester to Ashton: This project is anticipated to expand the existing roadway into a four-lane divided highway. Construction is anticipated to start in 2028.
- I-15 and US-20 Interchange: This project continues to make progress toward relocating I-15 Exit 119 to US-20 and realign US-20 through Idaho Falls to address safety and congestion concerns. Funding will allow for the purchase of private property for future construction.
With these projects now included in the draft Idaho Transportation Investment Program (ITIP), the public will have the opportunity to give feedback on this project and the department’s full list of planned projects from 2026-2032 during the annual comment period in July. Then the draft ITIP will be presented to the board for approval in September.
The board’s action today reflects continued investmenttargeting congestion and capacity in major corridors that were previously funded by TECM bondsas authorized by the Idaho Legislature. In East Idaho, TECM funds allowed for the construction at the South St. Anthony Interchange, which was previously unfunded.
This project and others were identified because they are existing high-priority corridor needs that will improve traffic flow and increase safety.
Traffic leaving U.S. Highway 20 to access South Rigby will be detoured on Monday through Wednesday, June 11, while the exit is closed for bridge repairs. The closure will be in effect from 8 a.m. to 5 p.m. and last until complete on Wednesday.
Travelers can take Exit 322 (North Rigby) or Exit 318 (County Line) as detours. Those leaving Rigby to get on to US-20 will still be able to use the southbound ramp at Exit 320 toward Idaho Falls as normal.
This closure will be noted on the Idaho 511 app and at https://511.idaho.gov.
The Idaho State Police (ISP) and the Idaho Transportation Department (ITD) urge drivers to make safe, sober choices behind the wheel following confirmation that the at-fault driver in a recent fatal crash on U.S. Highway 20 near Henry’s Lake had a blood alcohol content of 0.20 — more than twice the legal limit of 0.08.
The May 1 crash on one of the main corridors to Yellowstone National Park, which claimed the lives of seven people, occurred just as Idaho entered the 100 Deadliest Days — the period between Memorial Day and Labor Day when traffic fatalities typically rise due to increased summer travel, holidays, and impaired driving. Law enforcement and transportation officials say this preventable tragedy underscores the consequences of impaired driving.
“This tragedy should be a wake-up call,” ISP Captain Chris Weadick said. “No one plans to cause a crash or take a life when they get behind the wheel, but choices have consequences. Impaired driving isn’t just illegal — it’s deadly. If you see someone unfit to drive, speak up. Lives depend on it.”
Alcohol-related crashes remain one of the leading causes of traffic deaths in Idaho.
“Idaho’s roads are especially busy during the summer,” ITD Operations Manager Bryan Young said. “With more construction, increased travel, and an influx of visitors, we’re seeing more families and more drivers on the road. It only takes one impaired driver to change lives forever. This is a preventable problem, and it starts with each of us making responsible choices.”
DUI Prevention Tips
- Plan ahead: If you plan to drink, arrange for a designated driver, rideshare, taxi, or public transportation.
- Always buckle up: Seatbelts save lives and reduce injuries, though they do not replace the need for safe driving.
This summer, ISP and ITD are partnering to strengthen DUI enforcement and expand public outreach. We ask everyone to help protect lives by staying sober behind the wheel. The public is encouraged to report suspected impaired driving by calling *ISP (*477) or 911 if they observe erratic or dangerous behavior on the road.
REXBURG— One lane and full closures at Exits 332 and 333 off U.S. Highway 20 in Rexburg are ongoing today and into next week. These restrictions are required so contractors can drill deep foundations for the large overhead signs that will soon be the finishing touch on the Diverging Diamond Interchanges completed last fall.
Both of these Rexburg exits will see one lane closures in the areas where drilling work is occurring. Traffic control will move with equipment and the road fully open wherever possible.
Next Monday, May 19 and Tuesday, May 20 Exit 333 will be fully closed overnight from 7 p.m. to 7 a.m. ITD and contractor partners are working through the night so traffic can flow as usual through the daytime hours.
Large equipment, including a drill rig to reach the required 18-foot foundation depth, will need to be in the roadway underneath US-20 for work at both locations, reaching across and over the median concrete barriers. To keep everyone safe and be able to swiftly clean up any water or debris that the drilling creates, lane restrictions and closures have been deemed essential. ITD and contractor partners are committed to completing the work as quickly as possible to cause the least amount of traffic disruption.
“The foundation for the bridge and cantilever posts that will hold the large overhead signs has to be particularly deep,” Resident Engineer Curtis Calderwood stated. “We want them to be secure and have integrity in the wind. This is pretty well the last holdout for getting the exits truly finished.”
These restrictions and closures will be noted on the Idaho 511 app and at 511.idaho.gov.
