U.S. Route 91 is a north-south United States highway. The highway currently serves as a connection between the Cache Valley area of Utah and Idaho to the Salt Lake and Idaho Falls population centers. Prior the mid-1970s, U.S. 91 was a long haul route from Long Beach, California to the Canadian border north of Sweetgrass, Montana. The route has been largely replaced by Interstate 15. A portion of the highway's former route in California is currently State Route 91.

Route description

Utah

US-91 begins at Brigham City and winds its way through the Wellsville Mountains using Box Elder and Wellsville Canyons for its path to the Cache Valley. Along the way it passes Mantua and Lake Mantua and passes over Sardine Summit. Once entering Cache Valley it serves as the major thoroughfare of the valley. Logan is the largest city in the valley. Both the Utah and Idaho portions of Cache Valley are part of the Logan Utah Metropolitan Statistical Area.

The Utah section of US-91 is defined at Utah Code Annotated § 72-4-115(1).

Idaho

U.S. 91 continues serving the Idaho portion of the Cache Valley with Preston as the largest city. The highway passes by the Bear River Massacre Site, a National Historic Landmark, near Preston, and over the geologically significant Red Rock Pass, near Downey. The U.S. 91 corridor in Idaho's Cache Valley was the primary filming location for the 2004 movie Napoleon Dynamite.

After leaving Cache Valley, the highway then crosses back to rejoin Interstate 15. At Pocatello, U.S. 91, U.S. 30, and I-15 Business Loop separate from Interstate 15 and run concurrently, passing through a small portion of the Idaho State University campus. U.S. 30 separates from U.S. 91 near Pocatello's city hall at what was once the starting point of one of Idaho's first designated highways, the Yellowstone Park Highway. From this point the highway generally follows the original route of the Yellowstone Park Highway northeastward, until it reaches its terminus at its intersection with U.S. 26, south of Idaho Falls.

History

At its peak, from 1947 to 1965, U.S. 91 extended from the Pacific Ocean at Long Beach, California to Coutts, Alberta. North of Riverside, California, U.S. 91 mostly paralleled modern I-15. There are some parts where U.S. 91/I-15 had divergent paths. The first is from Littlefield, Arizona to Saint George, Utah where the two routes took different paths through the Arizona Strip. The second is the surviving portion of U.S. 91 from Brigham City to Downey, where Interstate 15 follows an old route of U.S. Route 191.

Utah first submitted a petition to AASHTO to have the U.S. 91 designation truncated in 1971. This petition was approved on June 21, 1971. However, the state did not take action until 1974. Utah officials co-ordinated a second petition with the transportation departments of California, Nevada and Arizona. In this unified petition officials in Utah proposed the number changeover take place in 1974. Nevada requested postponing the deletion of U.S. 91 as Nevada expected to complete the last piece of I-15 in 1975. Nevada officials suggested U.S. Route 40 be similarly truncated, as this highway largely duplicated Interstate 80 in the same states. Despite Nevada's request, the petition was submitted and approved in 1974.

Retracing the path of historic U.S. Route 91 is possible but difficult. In most cities the route of U.S. 91 is still in use as a local street or highway. In many rural areas, I-15 was literally built on top of the former U.S. 91.

The highway passed through the following states:

• California (until 1974)
• Nevada (until 1974)
• Arizona (10 miles (16 km) in the Arizona Strip, until 1974)
• Utah
• Idaho
• Montana (until 1980)

California

U.S. 91's original southern terminus was at the intersection of Atlantic Avenue (historically SR 15) and East Pacific Coast Highway (SR 1) in Long Beach. This intersection also marked the historic western terminus of US 6, which proceeded west from that intersection. East of the intersection, U.S. 91 proceeded east along East Pacific Coast Highway to Los Alamitos Circle.

The portions in California were replaced with:

• State Route 1 (Pacific Coast Highway from Atlantic Avenue to the Traffic Circle)
• State Route 19 (Lakewood Boulevard from the Traffic Circle to Lincoln Avenue)
• State Route 214 (route no longer a state highway — Carson Street and Lincoln Avenue)
• State Route 91
• Interstate 215
• Interstate 15

Nevada

The route of U.S. 91 in Nevada was replaced with I-15.

In Las Vegas, U.S. 91 was better known as Las Vegas Boulevard (State Route 604). The intersection of Las Vegas Boulevard and Fremont Street is the historic intersection with U.S. 93 and U.S. 95. Here, U.S. 466 left U.S. 91 and headed south on Fremont Street with U.S. 93 and 95. At this intersection, U.S. 93 and 95 left Fremont Street and turned north onto Las Vegas Boulevard, heading north with U.S. 91. One block further up, at Bonanza Road, U.S. 95 turned west until it hit Rancho Drive, then continued north. U.S. 91/93 stayed aligned with Las Vegas Boulevard.

Leaving Las Vegas, U.S. 91 followed I-15 to exit 112 (NV 170) to Mesquite (NV 144) and then to Hillside Drive into Arizona, where the road became Fairview Avenue.

Arizona

U.S. 91 entered Arizona from Nevada on Fairview Avenue and followed it northeast to Littlefield. Once Fairview Avenue crosses I-15, it became Cane Beds Road through downtown Beaver Dam and into Utah, where the road continued as Old Highway 91.

Utah

From the State Line to Saint George US-91 followed a semi-circular route that is now simply called Old Highway 91. Old Highway 91 continues to Santa Clara and what is now SR-18 to St. George.

From St. George to Springville US-91 is in the shadows of I-15. At places the old pavement is visible off to the side of the freeway; at others I-15 was paved over the old US-91.

US-91 first joined U.S. Route 89 in Springville at one of the oldest grade-separated interchanges in Utah (this portion is now State Route 51). From this junction to Logan the two highways ran mostly concurrent. This portion is mostly intact as US-89.

US-91 did have a unique route between Farmington and Ogden and where US-89/91 split and then rejoined on what is now State Route 126 and State Route 26. These highways form the Main Street through Kaysville and Layton; State Street from the Layton-Clearfield border to Main Street in Clearfield though the city of Sunset turning into 1900 West at the Sunset-Roy border, then following 1900 W to a junction with Riverdale Road in Roy, then following Riverdale Road through Riverdale, and then meeting back up with US-89 at Washington Blvd in Ogden.

Idaho

U.S. 91 formerly entered Idaho Falls along Yellowstone Highway, and returned to the course of modern I-15 north of town. The highway then proceeded north toward Monida Pass where the highway entered Montana. In some small towns streets used by the route are called "Old Highway 91".

Montana

In Montana the highway's alignment slightly changed with the construction of the Clark Canyon Dam. In Dillon the former route of the highway is now known as Atlantic Street and Montana Street.. North of Dillon I-15 was built on a new alignment. The highway formerly joined with U.S. Route 10 in Butte and formed the main street of Boulder. The highway was routed through Helena along what is now Montana Secondary Highway 518 and Montana Secondary Highway 229.

Major intersections

County	Location	Mile	Junction	Notes
Box Elder	Brigham City	0.000
		1.965
		3.920		Grade separated interchange, westbound exit, eastbound entrance
	Mantua	5.601	Mantua Road	Grade separated interchange, eastbound exit, westbound entrance
		6.638	500 North
		10.113	Sardine Summit	County line
Cache		12.669	Sherwood Hills Resort
	Wellsville	16.939
		19.177
		23.769
	Logan	26.651
		26.886
		27.148	,Utah State University,Bear Lake
	North Logan	29.819
	Smithfield	34.021
	Richmond	40.004
		43.694
		45.271	Utah/Idaho State line
Franklin	Preston
		8.389
		9.265
Bannock	Downey	37.070
		42.452
	Concurrency with I-15
	Pocatello	70.669		Concurrent with . Milemarker as listed by ITD reflecting concurrent route milemarker.
		3.450		Concurrent with . Milemarker as listed by ITD reflecting concurrent route milemarker.
		77.890
	Chubbuck	80.032
Bingham		97.052		Concurrent with
	Blackfoot	100.700
Bonneville		122.866	York Road/Old I-15B	ITD milepost log (01/29/08) reflects movement of and to the new Sunnyside Road alignment while ITD milepost log (01/29/08) still lists an intersection with at the old York Road alignment.
	Idaho Falls	4.526		Milemarker as listed by ITD reflecting prior concurrent route milemarker.

See also

• California State Route 91
• Interstate 15

References