|Length:||964.25 mi (1,551.81 km)|
|South end:||I‑10 in Laplace, LA|
| I-20 in Jackson, MS
I‑40 in West Memphis, AR
I-70 in East St. Louis, IL
I-80 near Joliet, IL
I-90 in Chicago, IL
|North end:||US 41 in Chicago, IL|
Interstate 55 (I-55) is a north–south Interstate Highway in the central United States. The highway travels from LaPlace, Louisiana, at I-10 to Chicago at U.S. Route 41 (US 41, Lake Shore Drive), at McCormick Place.
When it was realized that a national highway system was needed, the Federal Aid Highway Act of 1956 provided for a highway replacing the old Route 66 which I-55 filled. I-55 was originally constructed in the 1970s, to extend a section of Route 66 between I-294 and Gardner which had been converted into a freeway and had Interstate signage installed in 1960. During the rest of the 1960s, I-55 was built in portions throughout Illinois eventually connecting St. Louis to Chicago where it became the fourth direct route between them. As it goes southwards, most of the Interstate was purpose-built during the 1960s and 70s. The entire length was completed in 1979.
In Louisiana, I-55 runs nearly 66 miles (106 km) from south to north, from I-10 near Laplace (25 miles (40 km) west of New Orleans) to the Mississippi state line near Kentwood, Louisiana. Approximately 1⁄3 of the distance consists of the Manchac Swamp Bridge, a nearly 23-mile (37 km) causeway, often cited as the third-longest viaduct in the world.
In Mississippi, I-55 runs 290.5 miles (467.5 km) from the Louisiana border near Osyka, Mississippi to Southaven on the Tennessee border, just south of Memphis. Noteworthy cities and towns that I-55 passes through or close by to are McComb, Jackson, and Grenada. This highway parallels US 51 in its path roughly through the center of Mississippi. The eight miles (13 km) from Hernando to the Tennessee state line coincide with the newer I-69.
The Mississippi section of I-55 is defined in the Mississippi Code § 65-3-3.
I-55 in Tennessee lies entirely within the city of Memphis, passing through the southern and western parts of the city and providing a bypass of downtown for motorists who do not want to take I-240 and I-40 through downtown to cross the Mississippi River. The western portion of this highway, which passes through an industrialized section of the city, contains numerous low-clearance bridges, and also a very tight 270-degree cloverleaf turn northbound at Crump Boulevard. The Tennessee Department of Transportation currently has an interchange improvement project for this portion. Heavy truck traffic heading to and from Arkansas in this area is hence directed to detour via I-240 and I-40.
I-55 enters Arkansas from Tennessee as it crosses the Mississippi River on the Memphis & Arkansas Bridge. It overlaps I-40 for approximately 2.8 miles (4.5 km) in West Memphis. After separating from I-40, I-55 turns northward and runs with US 61, US 63, and US 64 until US 64 exits in through Marion. I-55/US 61/US 63 continue north through Crittenden County through rural farms of the Arkansas delta, including an interchange with Future I-555/US 63 in Turrell. I-55 passes through Blytheville, where it has a junction with Highway 18 before entering Missouri. I-55 parallels U.S. 61 in its path through Arkansas, which it continues to do after crossing into Missouri.
In Missouri, I-55 runs from the southeastern part of the state, at the Arkansas border, to St. Louis. In this city, I-44 merges in with I-55, and then I-64 (on the Poplar Street Bridge), when crossing the Mississippi River into Illinois.
Among the cities and towns served by I-55 in Missouri are Sikeston, Cape Girardeau, and St. Louis.
As noted above, I-55 parallels US 61 for most of its course through Missouri, from the Arkansas border to the Southern portion of St. Louis County.
I-55 largely follows the 1940 alignment of the former US 66, now Historic US 66 (Illinois Route 66 Scenic Byway), through Illinois. Entering Illinois from the south, I-55 near the I-270/I-70 split is referred to as the Paul Simon Freeway, named for former U.S. Senator Paul Simon, who began his political career in this region. Further north, between the St. Louis area and Springfield, I-55 is named the Vince Demuzio Expressway for former Illinois State Senator Vince Demuzio. I-55 parallels the third (1940) alignment of US 66 in Illinois from East St. Louis to Joliet, passing around the state capital of Springfield and likewise around the metro areas of Bloomington-Normal and Joliet. In the Chicago area, between the I-80 interchange near Joliet and I-55's eastern terminus at US 41 (Lake Shore Drive) in Chicago, the expressway is referred to as the Adlai E. Stevenson Expressway in honor of former Illinois governor Adlai E. Stevenson II, who was also the U.S. Ambassador to the United Nations under Presidents John F. Kennedy and Lyndon B. Johnson.
When this freeway was being planned during the 1960s, the Illinois Governor Otto Kerner, Jr., made an effort to have it routed close to the larger city of Peoria instead of the straighter route through the Bloomington-Normal area. This ultimately failed plan was ridiculed in the press as the so-called "Kerner Curve." The need for a freeway connection between Springfield and Peoria was later filled by the spur route I-155. This also connects with nearby Lincoln and Morton and forms a triangle between the three population centers in Central Illinois.
In 2009, officials in Green Bay, Wisconsin, began a campaign to have US 41 in that area designated as part of I-55, given that a section of US 41 in Wisconsin was in the process of being rebuilt to Interstate Highway standards. Some Green Bay area officials thought that designating US 41 as I-55 would have brought additional attention to that area. Such a segment of I-55 would have been disconnected from the remainder unless it was overlapped on I-94 between Chicago and Milwaukee, Wisconsin. An alternative was to designated the Green Bay–-to-Milwaukee section of US 41 as a spur of I-43. In December 2012, the American Association of State Highway and Transportation Officials and the Federal Highway Administration approved the renaming of the upgraded Wisconsin section of US 41 (between Russell Road just south of the Illinois-Wisconsin state line and Green Bay) as I-41.
- I‑10 in Laplace
- I‑12 in Hammond
- I-20 in Jackson (concurrent for two miles (3.2 km)}
- I-220 in Ridgeland
- I-69 in Hernando
- I‑40 in West Memphis (concurrent for three miles (4.8 km))
- I-155 in Hayti
- I-57 in Sikeston
- I-270 / I-255 at Mehlville just south of St. Louis (both intersections at the same interchange)
- I-44 in St. Louis. These two highways are concurrent for just three miles (4.8 km) within city of St. Louis.
- I-64 in St. Louis. These two highways are concurrent for just three miles (4.8 km) across the Mississippi River to East St. Louis, Illinois.
- I-70 in East St. Louis. These two highways concurrent for about sixteen miles (26 km) from East St. Louis until exit 20 near Troy.
- I-255 just west of Collinsville
- I-72 in Springfield (concurrent for six miles (9.7 km))
- I-155 west of Lincoln
- I-74 in Bloomington (concurrent for six miles (9.7 km))
- I-39 in Bloomington
- I-80 in Joliet
- I-355 in Bolingbrook
- I-294 in Burr Ridge
- I-90 / I-94 (Dan Ryan Expressway) in Chicago
- US 41 (Lake Shore Drive) in Chicago
- Spur to Jonesboro, Arkansas: I-555, under construction
- Caruthersville, Missouri to Dyersburg, Tennessee: I-155
- St. Louis, Missouri, area: I-255
- Spur to Peoria, Illinois: I-155
- In the southwestern suburbs of Chicago: I-355
- Staff (December 31, 2013). "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways As of December 31, 2013". Federal Highway Administration. Retrieved August 19, 2014.
- "Getting Around". City Visitors Guide. Retrieved August 24, 2013.
- Arkansas State Highway and Transportation Department (January 2, 2007) (PDF). General Highway Map, Crittenden County, Arkansas (Map). 1:62500. Cartography by Planning and Research Division. http://www.arkansashighways.com/maps/Counties/County%20PDFs/CrittendenCounty.pdf. Retrieved April 26, 2012.
- Arkansas State Highway and Transportation Department (January 11, 2010) (PDF). General Highway Map, Mississippi County, Arkansas (Map). 1:62500. Cartography by Planning and Research Division. http://www.arkansashighways.com/maps/Counties/County%20PDFs/MississippiCounty.pdf. Retrieved April 26, 2012.
- Unknown (January 1, 2000). "Despite dead-end for I-55's Kerner Curve, I-74 changed area forever". Peoria Journal-Star. Retrieved February 17, 2008.
- Green Bay Press Gazette, February 8, 2009
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