# List of Interstate Highways in Idaho

The Interstate Highways in Idaho are the segments of the Dwight D. Eisenhower National System of Interstate and Defense Highways owned and maintained by the Idaho Transportation Department (ITD) in the U.S. state of Idaho. The state has five Interstate Highways that total approximately 611 miles (983 km) in length.

## Mainline highways

| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| I-15 | 196.000 | 315.431 | I-15 near Woodruff | I-15 at Monida Pass | 01957-01-011957 | current | |
| I-15W | 62.850 | 101.147 | I-84 / US 30 near Declo | I-15 in Chubbuck | 01957-01-011957 | 01978-01-011978 | Became I-86 |
| I-80N | 275.650 | 443.616 | I-84 near Fruitland | I-84 near Black Pine | 01957-01-011957 | 01980-01-011980 | Became I-84 |
| I-84 | 275.650 | 443.616 | I-84 near Fruitland | I-84 near Black Pine | 01980-01-011980 | current | Designated as I-80N until 1980 |
| I-86 | 62.850 | 101.147 | I-84 / US 30 near Declo | I-15 in Chubbuck | 01978-01-011978 | current | Designated as I-15W until 1978 |
| I-90 | 73.888 | 118.911 | I-90 in State Line | I-90 at Lookout Pass | 01957-01-011957 | current | |
| I-180N | 3.620 | 5.826 | I-84 / US 30 in Boise | US 20 / US 26 in Boise | 01970-01-011970 | 01979-01-011979 | Became I-184 |
| I-184 | 3.620 | 5.826 | I-84 / US 30 in Boise | US 20 / US 26 in Boise | 01979-01-011979 | current | Designated as I-180N until 1979, completed in 1990 |
| Former ||||||||

## Business routes

| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| I-15 BL | 4.338 | 6.981 | I-15/US 91 exit 44 near McCammon | I-15/US 30/US 91 exit 47 in McCammon | — | — | |
| I-15 BL | 1.000 | 1.609 | I-15/US 30/US 91 exit 57 in Inkom | I-15/US 30/US 91 exit 58 in Inkom | — | — | |
| I-15 BL | 5.560 | 8.948 | I-15/US 30/US 91 exit 67 in Pocatello | I-15 exit 69 in Pocatello | — | — | US 30 and US 91 branches off I-15 at its southern end |
| I-15 BL | 4.802 | 7.728 | I-15 exit 89 southwest of Blackfoot | I-15/US 26 exit 93 in Blackfoot | — | — | I-15 and US 26 begin concurrency at northern end |
| I-15 BL | 7.230 | 11.636 | I-15/US 26 exit 116 near Idaho Falls | I-15/US 20 Bus. exit 118 in Idaho Falls | — | — | Concurrent with Us 26 at south end and US 20 Bus. at north end |
| I-84 BL | 12.557 | 20.209 | I-84/US 20/US 26/US 30 exit 27 in Caldwell | I-84/US 30/SH-55 exit 38 in Nampa | — | — | |
| I-84 BL | — | — | I-84/US 30 exit 49 west of Boise | I-84/US 20/US 26/US 30 exit 54 in Boise | — | — | Now part of I-184, US 20, and US 26 |
| I-84 BL | 5.985 | 9.632 | I-84/US 20/US 26/US 30 exit 90 near Mountain Home | I-84/US 26/US 30 exit 99 near Mountain Home | — | — | |
| I-84 BL | — | — | I-84/US 26/US 30/SH-78 exit 112 in Hammett | I-84/US 26/US 30 exit 114 near Hammett | — | — | Runs concurrent with SH-78 at west end |
| I-84 BL | 1.425 | 2.293 | I-84/US 26/US 30 exit 120 in Glenns Ferry | I-84/US 26/US 30 exit 121 in Glenns Ferry | — | — | |
| I-84 BL | 3.518 | 5.662 | I-84/US 26/US 30 exit 137 near Bliss | I-84/US 26 exit 141 in Bliss | — | — | Runs concurrent with US 30 near whole length. Road continues as US 26 at east end |
| I-84 BL | 6.56 | 10.56 | I-84/SH-27 exit 208 near Burley | I-84/US 30/SH-24 near Heyburn | — | — | Entirely concurrent with SH-27 at west end then US 30 to east end. Road continues as SH-24 |
| I-86 BL | 6.475 | 10.421 | I-86/US 30/SH-37 exit 36 near Neeley | I-86/US 30/SH-39 exit 40 in American Falls | 01972-01-011972 | current | Concurrent with SH-39 toward east end |
| I-90 BL | 5.640 | 9.077 | I-90 exit 2 west of Post Falls | I-90 exit 6 in Post Falls | — | — | |
| I-90 BL | 3.834 | 6.170 | I-90 exit 11 near Coeur d'Alene | I-90 exit 15 in Coeur d'Alene | — | — | |
| I-90 BL | 1.4 | 2.3 | I-90 exit 49 near Kellogg | I-90 exit 51 in Kellogg | — | — | |
| I-90 BS | 3.966 | 6.383 | I-90 exit 57 in Osburn | E. Mullan Ave. in downtown Osburn | — | — | Originally a business loop that ran from exit 57 to exit 60 to Silverton via Silver Valley Road. Split into two separate spurs |
| I-90 BS | 0.12 | 0.19 | I-90 exit 60 in Silverton | Silver Valley Rd south of Silverton | — | — | Part of original loop that once ran from I-90 exit 57 in Osburn to exit 60 in Silverton via Silver Valley road. Split into two separate spurs |
| I-90 BL | 1.243 | 2.000 | I-90 exit 61 near Wallace | I-90 exit 62 in Wallace | — | — | Originally part of I-90 that contained a traffic signal before entering Wallace. Became I-90BL when I-90 was rerouted north as a full freeway |
| I-90 BL | 1.000 | 1.609 | I-90 exit 68 in Mullan | I-90 exit 69 near Mullan | — | — | |
| Former ||||||||