Interstate 39
Interstate 39 is a highway in the Midwestern United States. I-39 runs from Normal, Illinois at I-55 to Wisconsin Highway 29 in Rib Mountain, Wisconsin, approximately southwest of Wausau. I-39 was designed to replace U.S. Route 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.
In Illinois, the route has a total length of. In Wisconsin, I-39 has a distance of. With the exception of an segment around Portage, the Interstate shares a route with at least one other route number in I-39's entirety. From Rockford to Portage, I-39 is concurrent with I-90. I-94 joins the pair in Madison until Portage. At in length, this concurrency of three Interstates is the longest in the country. From Portage northward, US 51 is co-signed with the Interstate and has exit numbers based on its mileage.
Route description
Illinois
In Illinois, I-39 begins at Interstate 55, north of the Bloomington-Normal, Illinois, area alongside of Route 251. It runs north largely through rural areas from the city of Normal. About north of the city, I-39 crosses the Illinois River over the Abraham Lincoln Memorial Bridge, which is long. Just north of the Illinois River, I-39 runs east of the cities of LaSalle and Peru before intersecting Interstate 80. North of I-80, the wind turbines of the Mendota Hills Wind Farm can be seen from milepost 72 at Mendota north to near Paw Paw. I-39 intersects with I-88 near Rochelle. Further north, I-39 crosses the Kishwaukee River before meeting US 20 on the south side of Rockford. I-39 then runs east concurrently with US 20 to where the interstate joins the Jane Addams Memorial Tollway and Interstate 90 near Cherry Valley. I-39 and I-90 head north together to South Beloit. There is a toll plaza just south of Rockton Road. US 51 leaves I-39/90 at Illinois 75 in South Beloit, while I-39/90 continue north into Wisconsin.For all but that Interstate 39 is in Illinois, it is designated concurrently with U.S. Route 51. The southern terminus of I-39 is less than from Interstate 74 as it runs around Normal.
Wisconsin
I-39 enters from Illinois along with I-90, passing under Stateline Road, and bypasses Beloit to the east. East of the town, the route has a cloverleaf interchange that serves as the terminus for both WIS 81—which heads westward into Beloit—and I-43, which provides access to Milwaukee. I-39/I-90 has 3 interchanges that serves Beloit. The I-39/90 concurrency continues to the north and is joined by WIS 11 about north of the I-43 interchange. The route bypasses Janesville to the east, although interchanges with US 14 and WIS 26 provide access to the town. There are 4 exits that serve Janesville. The route continues generally to the north, crossing the Rock River before having an interchange with WIS 59 that provides access to Edgerton to the west. Subsequently, the route enters Dane County as it passes west of Lake Koshkonong. It is joined by US 51 from Edgerton and serves as the southern terminus of WIS 73. US 51 leaves the route to the north, about east of Stoughton. The Interstate gradually turns westward around Utica to an interchange with CTH N. It then turns gradually back to the north and interchanges with US 12 and US 18 in Madison. I-39 and I-90 bypass Madison to the east, and I-94 joins the concurrency at the eastern terminus of WIS 30, an interchange known as the Badger Interchange. About to the north, the highway crosses US 151, which includes a south-side access to High Crossing Boulevard. The last two Madison area interchanges are US 51 three miles northwest of the US 151 interchange and WIS 19 another mile northwest of the US 51 interchange. Access is provided to CTH V just west of DeForest further north. I-39/I-90/I-94 enter Columbia County north-northwest of CTH V.The Interstates cross WIS 60 at an interchange north of the county line west of Arlington and CTH CS at another interchange further north near Poynette. The highway crosses the Wisconsin River north of CTH CS. At further along the route from the river, I-39 leaves the concurrency with I-90 and I-94 and turns northward while the other two interstates turn northwest. WIS 78 terminates at this interchange and heads southwest. This is the starting point of the segment of freeway that carries the I-39 route alone. The interstate crosses WIS 33, the first of 3 interchanges accessing Portage, north of I-90/I-94. After crossing the Wisconsin River again, I-39 crosses the second interchange—this one with WIS 16 and turns northeast to an interchange with US 51. The US route joins the Interstate and both turn north once again and leave the Portage area and, after, enter Marquette County.
WIS 23 joins I-39/US 51 northbound, from the county line. The three highways pass along Buffalo Lake and encounter a south-side half interchange with CTH D in the town of Packwaukee. WIS 23 leave the concurrency to the east heading toward Montello at WIS 82 near Oxford. and the freeway takes a due north route to pass Westfield. I-39/US 51 enters Waushara County north of Westfield. Four miles north of the county line, I-39 / US 51 junction with WIS 21 in Coloma. I-39/US 51 meet an interchange in Hancock with CTH V further north and WIS 73 crosses in Plainfield after another. This is south of the Portage County line. In Portage County, I-39/US 51 takes a straight due north trajectory which provides access to CTH D, CTH W and WIS 54 over. The WIS 54 interchange and the CTH B interchange a mile and a half north of it provide access for Plover. The next four interchanges—CTH HH, US 10 Eastbound / WIS 66 Westbound, Stanley Street and Business US 51 provide access to Stevens Point. Amongst these interchanges, the freeway turns northwestward, bypassing the city to the east and north. I-39/US 51 cross two more interchanges while in Portage County: Casimir Road northwest of Stevens Point, and Westbound US 10 two miles north of Casimir Road. The freeway then parallels the Wisconsin River for to an Interchange with CTH DB east of Lake DuBay and south of the Marathon County line.
WIS 34 terminates at an interchange with I-39/US 51 in Knowlton northwest of the freeway's entry into Marathon County. The freeway turns due north from this interchange. WIS 153 crosses the freeway four miles further north in Mosinee. Maple Ridge Road crosses after another as the freeway turns northeastward into Kronenwetter. An interchange with Business US 51 is just south of the Wisconsin River crossing after from Maple Ridge Road. I-39 ends further north at the interchange with WIS 29 East just southwest of Wausau.
History
When the Interstate Highway System was first being planned, Illinois made a request for a north–south highway from South Beloit to Salem. The project was deemed a low priority and was shelved. US 51, which ran mostly down the middle of the state, became a heavily traveled two-lane arterial road, experiencing many crashes and earning the nickname "Killer 51".In the late 1960s and early 1970s, a major supplemental freeway system plan was proposed, with the goal of providing Illinois residents access to freeways within 30 minutes or less. One of the proposed routes, FAP 412, was a route that would extend from US 20 in Rockford to I-57 just north of Salem, similar to the earlier requested route. Due to traffic counts, only the portion between Rockford and Decatur was prioritized.
Over the course of the 1970s, planning for the US 51 supplemental freeway took place in earnest. However, debate ensued over what type of highway should be built. IDOT wanted the entire highway built to Interstate Highway standards, but a transportation committee established to review the proposed supplemental freeway system recommended only Interstate construction between Rockford and I-80. The highway from Oglesby south to Decatur was recommended to be a at-grade expressway, utilizing the existing road where possible. After a decade of lobbying by interest groups, Governor James R. Thompson announced in 1986 that US 51 would be rebuilt to Interstate standards from Oglesby to Bloomington–Normal. However, due to funding concerns and local opposition, it was decided that US 51 would not be built to Interstate standards between Bloomington and Decatur, and it was instead upgraded to an at-grade expressway.
The first segment of the freeway opened 1984 from IL 5 in Rochelle, to US 20 in Rockford. When the freeway was completed south from IL 5 to I-80 in 1986, IDOT officially requested an Interstate designation for the new highway, and I-39 was officially designated. By December 1987, construction on the section of I-39 between I-80 and IL 251 was finished. The next section, between IL 251 and I-55 in Bloomington-Normal, was completed by 1992, although this stretch of the highway was opened in several phases as completed.
In December 1989, the section from Bloomington–Normal to Hudson opened, a distance of about. In early September 1992, another segment opened from IL 116 north to IL 17.
In Wisconsin, the highway was officially designated in 1992. In October 1993, AASHTO established part of I-39 in its northern section between Rockford and Rib Mountain, Wisconsin, then designated I-39 along existing portions of I-90, I-94, and US 51. However, this part of the highway was not marked as I-39 for another four years, primarily because the Wisconsin Department of Transportation had to reconstruct the interchange connecting I-90 and I-94 with WIS 78 near Portage. Signs denoting I-39 were placed along the highway in Wisconsin until 1996, when the section between Portage and Rib Mountain received its signs. This occurred after then Governor Tommy Thompson designated the stretch between Portage and Wausau in 1996 after a five-year push to get the Interstate designation approved. The remaining segment along I-90/I-94 was not signed for I-39 until late 1998 The section between the I-90/I-94 interchange and US 51's interchange in Portage was previously a part of WIS 78. That route was truncated back to its current terminus when the Interstate's designation went into effect. The designation of I-39 violated Wisconsin's rule of not having any state trunk highway number duplicated—Interstate, US or state—as WIS 39 already existed.