The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, or the Eisenhower Interstate System, is a network of controlled-access highways that forms part of the National Highway System in the United States. The system extends throughout the contiguous United States and has routes in Hawaii, Alaska, and Puerto Rico.
Interstate 81 (I-81) is a north–south Interstate Highway in the eastern part of the United States. Its southern terminus is at I-40 in Dandridge, Tennessee; its northern terminus is on Wellesley Island, New York at the Canadian border, where the Thousand Islands Bridge connects it to Highway 137 and ultimately to Highway 401, the main Ontario freeway connecting Detroit via Toronto to Montreal. The major metropolitan areas along the route of I-81 include the Tri-Cities of Tennessee; Roanoke in Virginia; Harrisburg and the Wyoming Valley in Pennsylvania; and Syracuse in New York.
Interstate 515 (I-515) was a 20.54-mile-long (33.06 km) spur route of I-15 in the US state of Nevada that ran from the junction of I-15, US 93 and US 95 in Downtown approximately 20 miles (32 km) southeast to just north of Railroad Pass in southeastern Henderson. The freeway connected traffic headed from Boulder City and Henderson to Downtown Las Vegas via a direct, high-speed route, and it ran concurrently with, US 93, and US 95 along its entire length.
A concurrency in a road network is an instance of one physical roadway bearing two or more different route numbers. When two roadways share the same right-of-way, it is sometimes called a common section or commons. Other terminology for a concurrency includes overlap, coincidence, duplex, triplex, multiplex, dual routing or triple routing.
Interstate 295 (I-295), also known as the Fayetteville Outer Loop, is a partially completed Interstate-grade planned 34-mile-long (55 km) bypass around the western side of Fayetteville, North Carolina, United States. As of July 2024, it stretches for 22 miles (35 km) from US Highway 401 (US 401) in western Fayetteville to I-95 and US 13 near Eastover. The final section between US 401 and I-95 near Parkton is being constructed in segments and is expected to be completed around 2026. A 6.3-mile-long (10.1 km) segment from I-95 east of Parkton to Camden Road west of Hope Mills is signed as North Carolina Highway 295 (NC 295). NC 295 was also used as temporary designations for the highway before I-295 was signed.
Interstate 86 (I-86) is an east–west intrastate Interstate Highway located entirely within the state of Idaho. It runs approximately 63 miles (101 km) from an intersection with I-84 east of Declo in rural Cassia County, to an intersection with I-15 in Chubbuck, just north of Pocatello. The highway is part of the main route from Boise and Twin Falls to Idaho Falls and the upper Snake River region.
Interstate 495 (I-495) is an 11.47-mile-long (18.46 km) auxiliary Interstate Highway in the US state of Delaware. The highway, named the Vietnam Veterans Memorial Highway, serves as a six-lane bypass of I-95 around the city of Wilmington. I-495 begins at an interchange with I-95 and I-295 near Newport to the southwest of Wilmington. From here, the road heads east to the Port of Wilmington, where it turns northeast and crosses the Christina River as it heads to the east of downtown Wilmington. Upon reaching Edgemoor, I-495 runs between the Delaware River to the east and U.S. Route 13 (US 13) to the west, continuing to Claymont. In Claymont, I-495 turns north and merges into northbound I-95 at an interchange with Delaware Route 92 (DE 92) just south of the Pennsylvania state line.
Interstate 110 (I-110) is a 0.92-mile (1.48 km) auxiliary Interstate Highway in El Paso, Texas, extending from I-10 south along U.S. Highway 54 (US 54), then turning west, and finally turning south into Mexico. I-110 provides access from I-10 to the Bridge of the Americas, which spans the Rio Grande to connect with Avenida Abraham Lincoln in Ciudad Juárez, Mexico. I-110 is currently the only auxiliary Interstate to connect directly with Mexico, and one of only two to connect to an international border, the other being I-190 in New York.
Interstate 190 (I-190) is an auxiliary Interstate Highway in the US state of South Dakota. The route runs for about two miles (3.2 km) connecting I-90 to downtown Rapid City. The entire route is concurrent with US Highway 16 (US 16). It is the westernmost auxiliary route of I-90 and its only auxiliary route west of the Mississippi River.
Interstate 41 (I-41) is a 175.00-mile-long (281.64 km) north–south Interstate Highway connecting the interchange of I-94 and U.S. Route 41 (US 41), located about a mile (1.6 km) south of the Wisconsin–Illinois border at the end of the Tri-State Tollway in metropolitan Chicago, to an interchange with I-43 in metropolitan Green Bay, Wisconsin. The designation travels concurrently with US 41 for its entire length, as well as portions of I-894, US 45, I-43, and sections of I-94 in Wisconsin and Illinois. The route was officially added to the Interstate Highway System on April 7, 2015, and connects Milwaukee and Green Bay with the Fox Cities.
US Highway 27 (US 27) is a part of the US Highway System that now runs from Miami, Florida, to Fort Wayne, Indiana. In the US state of Michigan, it was a north–south state trunkline highway that entered the state south of Kinderhook and ended south of Grayling. Its route consisted of a freeway concurrency with Interstate 69 (I-69) from the state line north to the Lansing area before it followed its own freeway facility northward to St. Johns. From there north to Ithaca, US 27 was an expressway before continuing as a freeway to a terminus south of Grayling.
Interstate 95 (I-95), the main Interstate Highway on the East Coast of the United States, serves the Atlantic Coast of the US state of Georgia. It crosses into the state from Florida at the St. Marys River near Kingsland and travels to the north past the cities of Brunswick and Savannah to the South Carolina state line at the Savannah River near Port Wentworth. The route also passes through the cities of Richmond Hill, Darien, and Woodbine. I-95 in Georgia has the unsigned designation of State Route 405 (SR 405).
Interstate 680 (I-680) in Nebraska and Iowa is the northern bypass of the Omaha–Council Bluffs metropolitan area. I-680 spans 16.49 miles (26.54 km) from its southern end in western Omaha, Nebraska, to its eastern end near Crescent, Iowa. The freeway passes through a diverse range of scenes and terrains—the urban setting of Omaha, the Missouri River and its valley, the rugged Loess Hills, and the farmland of Pottawattamie County, Iowa.
Interstate 40 (I-40) is a part of the Interstate Highway System that travels 2,556.61 miles (4,114.46 km) from Barstow, California, to Wilmington, North Carolina. In North Carolina, I-40 travels 420.21 miles (676.26 km) across the entirety of the state from the Tennessee state line along the Pigeon River Gorge to U.S. Highway 117 (US 117) and North Carolina Highway 132 (NC 132) in Wilmington. I-40 is the longest Interstate Highway in North Carolina and is the only Interstate to completely span the state from west to east.
Interstate 69 (I-69) is a part of the Interstate Highway System that will eventually run from the Mexican border in Texas to the Canadian border at Port Huron, Michigan. In Michigan, it is a state trunkline highway that enters the state south of Coldwater and passes the cities of Lansing and Flint in the Lower Peninsula. A north–south freeway from the Indiana–Michigan border to the Lansing area, it changes direction to east–west after running concurrently with I-96. The freeway continues to Port Huron before terminating in the middle of the twin-span Blue Water Bridge while running concurrently with I-94 at the border. There are four related business loops for I-69 in the state, connecting the freeway to adjacent cities.
Interstate 29 (I-29) is a north–south Interstate Highway in the midwestern United States. In the state of South Dakota, I-29 traverses on the eastern side of the state from the Iowa border near Sioux City to the North Dakota border near New Effington. On its route, I-29 passes through western portions of Sioux Falls, the state's largest city. It travels 252.5 miles (406.4 km) in the state, the longest stretch of any of the four states through which it passes. I-229, the highway's lone auxiliary route in South Dakota, serves as a bypass around southern and eastern Sioux Falls.
Interstate 87 (I-87) is a partially completed Interstate Highway in the US state of North Carolina, the shortest designated primary Interstate Highway at 12.90 miles (20.76 km) long. The completed portion is in eastern Wake County, between Raleigh and Wendell; the majority of the completed route is known as the Knightdale Bypass, while the remaining three miles (4.8 km) follows the Raleigh Beltline (I-440). It is planned to continue northeast through Rocky Mount, Williamston, and Elizabeth City, ending in Norfolk, Virginia. It is signed as north–south, in keeping with the sign convention for most odd-numbered interstates, but the route goes primarily east–west, with the eastern direction aligning to the north designation. The entire route is concurrent with US Highway 64 (US 64), with portions also concurrent with I-440 and US 264.
