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.
The United States Numbered Highway System is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these highways were coordinated among the states, they are sometimes called Federal Highways, but the roadways were built and have always been maintained by state or local governments since their initial designation in 1926.
Interstate 24 (I-24) is an Interstate Highway in the Midwestern and Southeastern United States. It runs diagonally from I-57, 10 miles (16 km) south of Marion, Illinois, to Chattanooga, Tennessee, at I-75. It travels through Illinois, Kentucky, Tennessee, and Georgia. As an even-numbered Interstate, it is signed as an east–west route, though the route follows a more southeast–northwest routing, passing through Nashville, Tennessee. The numbering deviates from the standard Interstate Highway System grid, lying further north than its number would indicate west of Nashville. The short segment within Georgia bears the unsigned designation State Route 409 (SR 409).
Interstate 39 (I-39) is a highway in the Midwestern United States. I-39 runs from Normal, Illinois, at I-55 to State Trunk Highway 29 (WIS 29) in the town of Rib Mountain, Wisconsin, which is approximately six miles (9.7 km) south of Wausau. I-39 was designed to replace U.S. Route 51 (US 51), which, in the early 1980s, was one of the busiest two-lane highways in the United States. I-39 was built in the 1980s and 1990s.
Interstate 55 (I-55) is a major Interstate Highway in the central United States. As with most primary Interstates that end in a five, it is a major cross-country, north–south route, connecting the Gulf of Mexico to the Great Lakes. The highway travels from LaPlace, Louisiana, at I-10 to Chicago, Illinois, at U.S. Route 41, at McCormick Place. The major cities that I-55 connects to are New Orleans, Louisiana; Jackson, Mississippi; Memphis, Tennessee; St. Louis, Missouri; and Chicago, Illinois.
Interstate 57 (I-57) is a north–south Interstate Highway in Missouri and Illinois that parallels the old Illinois Central Railroad for much of its route. It runs from Sikeston, Missouri, at I-55 to Chicago, Illinois, at I-94. I-57 essentially serves as a shortcut route for travelers headed between the Southern U.S. and Chicago, bypassing St. Louis, Missouri, and Springfield, Illinois. Between the junction of I-55 and I-57 in Sikeston and the junction of I-55 and I-90/I-94 in Chicago, I-55 travels for 436 miles (702 km), while the combination of I-57 and I-94 is only 396 miles (637 km) long between the same two points. In fact, both the control cities on the overhead signs and the destination mileage signs reference Memphis along southbound I-57, even as far north as its northern origin at I-94 in Chicago. Likewise, at its southern end, Chicago is the control city listed for I-57 on signs on northbound I-55 south of Sikeston, even though I-55 also goes to Chicago. A southward extension of I-57 from its current southern terminus to Little Rock, Arkansas, is currently in various stages of development.
Interstate 43 (I-43) is a 191.55-mile-long (308.27 km) Interstate Highway located entirely within the US state of Wisconsin, connecting I-39/I-90 in Beloit with Milwaukee and I-41, U.S. Highway 41 (US 41) and US 141 in Green Bay. State Trunk Highway 32 (WIS 32) runs concurrently with I-43 in two sections and I-94, I-894, US 10, US 41, US 45, and WIS 57 overlap I-43 once each. There are no auxiliary or business routes connected to I-43, though an alternate route to direct traffic during road closures is signed along local and state highways from Milwaukee County north into Brown County.
Interstate 69 (I-69) is an Interstate Highway in the United States currently consisting of eight unconnected segments. The longest segment runs from Evansville, Indiana, northeast to the Canadian border in Port Huron, Michigan, and includes the original continuous segment from Indianapolis, Indiana, to Port Huron of 355.8 miles (572.6 km). The remaining separated segments are variously completed and posted or not posted sections of an extension southwest to the Mexican border in Texas. Of this extension—nicknamed the NAFTA Superhighway because it would help trade with Canada and Mexico spurred by the North American Free Trade Agreement (NAFTA)—seven pieces in Laredo, Texas; Pharr, Texas; Brownsville, Texas; Corpus Christi, Texas; Houston, Texas; northwestern Mississippi; and Memphis, Tennessee, have been built or upgraded and signposted as I-69. Indiana completed the fifth segment that extends I-69 through that state in August 2024.
U.S. Route 45 is a major north-south United States highway and a border-to-border route, from Lake Superior to the Gulf of Mexico. A sign at the highway's northern terminus notes the total distance as 1,297 miles (2,087 km).
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.
Interstate 164 (I-164) was a spur highway of I-64, between that highway and U.S. Highway 41 (US 41) in Evansville, Indiana. I-164, also known as the Robert D. Orr Highway, had a total length of 21.24 miles (34.18 km) and was the only auxiliary route of I-64 in Indiana. Requested as an Interstate and approved in 1968, the freeway was opened to traffic on August 2, 1990.
State Route 162 is a state highway in the U.S. state of California that runs roughly west–east through the Coast Ranges and the Sacramento Valley to the western slopes of the Sierra Nevada. It begins at U.S. Route 101 near Longvale, in Mendocino County, and ends at Brush Creek, in Butte County. For most of its length, it is a two lane, undivided highway. SR 162 is not signed as a contiguous route through Mendocino National Forest in Mendocino and Glenn counties. Instead, the portion inside the national forest is federally maintained by the U.S. Forest Service as Forest Highway 7 (FH 7), and is not included in the state route logs.
The Wisconsin State Trunk Highway System is the state highway system of the U.S. state of Wisconsin, including Wisconsin's segments of the Interstate Highway System and the United States Numbered Highway System, in addition to its other state trunk highways. These separate types of highways are respectively designated with an I-, US, or STH- prefix. The system also includes minor roads designated as Scenic Byways, four routes intended to promote tourism to scenic and historic areas of the state; and as Rustic Roads, lightly traveled and often unpaved local roads which the state has deemed worthy of preservation and protection. The state highway system, altogether totaling 11,753 miles (18,915 km) across all of Wisconsin's 72 counties, is maintained by the Wisconsin Department of Transportation (WisDOT).
