
West
U.S. 20 west enters the Gem State across Targhee Pass and the Continental Divide in the Henrys Lake Mountains.
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U.S. 20 heads south through Fremont County from the state line to St. Anthony.
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The city of Ashton is 45 miles to the southwest, followed by Idaho Falls in 98 miles.
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U.S. 20 parallels Howard Creek west across Henrys Lake Mountains.
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U.S. 20 enters the Island Park city limits just ahead of Henrys Lake Flat.
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Idaho Highway 87 ties into U.S. 20 southeast from Henrys Lake.
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ID 87 heads 9.13 miles northwest to the Montana state line at Raynolds Pass. Montana Highway 87 extends north from there to Missouri Flats and U.S. 287.
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MSR 87 and U.S. 287 north lead 58 miles from U.S. 20 to the Montana town of Ennis.
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E 5100 N stems west from U.S. 20 to Henrys Lake State Park.
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Reassurance marker posted near milepost 397 on Henrys Lake Flat.
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Curving westward, U.S. 20 advances south into the community of Macks Inn.
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U.S. 20 crosses the Henrys Fork of the Snake River south at Macks Inn.
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Macks Inn is 31 miles north of Ashton.
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U.S. 20 west at Yale-Kilgore Road west.
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U.S. 20 runs just east of the Henrys Fork Snake River at Last Chance.
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Mesa Falls Scenic Drive follows Old ID 47 south to Warm River.
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U.S. 20 crosses the Henrys Fork river again over the Osborne Bridge ahead of milepost 379.
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High Point Road (Forest Road 319) heads west from U.S. 20 to Big Bend Ridge, southeast of High Point.
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U.S. 20 advances 11 miles south from Graveyard Flats Road to Ashton.
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U.S. 20 lowers at a 6% grade from Anderson Mill Canyon Road (N.F. Road 164) south from Big Bend Ridge.
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Reassurance marker posted south of Anderson Mill Canyon Road.
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Descending toward Ashton, U.S. 20 leaves Caribou-Targhee National Forest beyond milepost 365.
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U.S. 20 west spans Henrys Fork river after the intersection with Boat Dock Road.
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The Teton Range appears along the eastern horizon beyond agricultural land along U.S. 20.
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The city of Ashton spreads along the east side of U.S. 20 from Whitepines Avenue south to 3500 E.
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ID 47 spurs 12.43 miles northeast from U.S. 20 at Ashton to Marysville and Warm River.
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Idaho Highway 47 formerly comprises a full loop east from U.S. 20 between Ashton and a point south of Last Chance. State maintenance ends north of Warm River at the Bear Gulch Trailhead, where ID 47 becomes Mesa Falls Scenic Drive (N.F. Road 294).
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ID 47 (Main Street) east connects with ID 32 (N 3600 E) south one mile from U.S. 20. ID 32 constitutes a 28.36 mile long loop southeast to ID 33 near Tetonia. The Teton County seat of Driggs is located along ID 33.
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Turning southwest at 3500 E, U.S. 20 leaves Ashton alongside a Union Pacific Railroad line.
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U.S. 20 advances 14 miles south from Ashton to the Fremont County seat of St. Anthony.
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U.S. 20 curves more southwesterly from E 1000 N to a weigh station at mile marker 356.
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U.S. 20 west crosses the Fall River just ahead of milepost 354.
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U.S. 20 expands to a controlled access expressway southwest of 3000 E.
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U.S. 20 passes through the unincorporated community of Chester between 800 N and 2900 E.
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Continuing southwest from Chester, U.S. 20 reaches Sugar City in 14 miles and Rexburg in 18 miles.
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U.S. 20 diverges from the adjacent UP Railroad across Crosscut Canal at 700 N beyond this shield assembly. The bridge spanning the canal was built in 1973.
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Page Updated Wednesday March 25, 2026.