U.S. Route 93 in Idaho

U.S. Route 93 (US 93) is a north–south U.S. Highway in the U.S. state of Idaho.

Route description
US 93 enters southern Idaho from Nevada, immediately north of the border casino town of Jackpot. Heading northbound in Twin Falls County, it passes through Rogerson and Hollister towards Twin Falls. West of the city, US-93 turns and runs east–west for a few miles, parallel with US-30. This section is Pole Line Road; the highway returns to its north–south orientation in Twin Falls at the intersection of Pole Line Road and Blue Lakes Boulevard.

North of Twin Falls, US-93 crosses the Snake River Canyon via the Perrine Bridge, 486 ft above the water. Approximately 3 mi north of the bridge, the highway intersects with Interstate 84 at Exit 173.

Further north in Shoshone, US-93 connects with the southern terminus of State Highway 75, the former route of US-93 to Ketchum and over Galena Summit (8701 ft above sea level) to Stanley and Clayton. Present-day US-93 diverts in a northeasterly route to Richfield, Carey, the Craters of the Moon, and Arco. Between Shoshone and Arco, the highway runs concurrently with the east–west US-26, and also with US-20 between Carey and Arco.

From Arco, the highway turns northwest and climbs the Big Lost River valley through Mackay. This section provides views of the Lost River Range to the northeast of the highway, including Borah Peak, the highest point in the state at 12662 ft. Mackay Dam and reservoir are on the southwest side of the highway. The highway crosses the Willow Creek Summit at 7161 ft (web-cam) and later descends into Grand View Canyon and heads into the city of Challis.

US-93 creates the northern terminus of State Highway 75 just south of Challis and takes over as the northern leg of the Salmon River Scenic Byway. It descends with the Salmon River as it winds north around the edge of the Lost River and Lemhi mountain ranges into the city of Salmon at 4004 ft.

Continuing north, the US-93 runs along portions of the Lewis and Clark Trail. The highway follows the descending northbound river until North Fork at 3620 ft, where the Salmon River makes a left turn to flow west across the state to Riggins. US-93 continues north, climbing the North Fork of the Salmon River into the Bitterroot Range, passing through the Salmon-Challis National Forest and Gibbonsville. The highway exits Idaho at Lost Trail Pass (web-cam) at 7014 ft and enters Montana toward the Bitterroot Valley. West of the highway at the pass is the Lost Trail Powder Mountain ski area, with terrain in both states.

History
US-93 was established in 1926, initially using the modern-day route of SH-75 between Shoshone and Challis. The highway was re-aligned to its modern route via Arco in 1977, replacing an alternative route.

In 2010, the 5.5 mi Pole Line Road bypass around Twin Falls opened to traffic. US 93 was re-routed to the new bypass, while the old route was signed as US 93 Business.