Interstate 39
I-39 highlighted in red
Route information
Maintained byIDOT,ISTHA andWisDOT
Length	306.14 mi[1] (492.68 km)
Existed	1986–present
NHS	Entire route
Major junctions
South end	I-55 /US 51 inNormal, IL
Major intersections	I-80 inLaSalle, IL I-88 Toll /IL 110 (CKC) inRochelle, IL I-90 Toll inCherry Valley, IL I-43 /WIS 81 inBeloit, WI I-94 /WIS 30 inMadison, WI I-90 /I-94 /WIS 78 inPortage, WI
North end	US 51 /WIS 29 nearRothschild, WI
Location
Country	United States
States	Illinois,Wisconsin
Counties	IL:McLean,Woodford,Marshall,LaSalle,Lee,Ogle,Winnebago WI:Rock,Dane,Columbia,Marquette,Waushara,Portage,Marathon
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future
Illinois State Highway System Interstate US State Tollways Scenic
Wisconsin State Trunk Highway System Interstate US State Scenic Rustic
←IL 38 IL →US 40 ←WIS 38 WI →WIS 39

Interstate 39 (I-39) is a north–southInterstate Highway in Illinois and Wisconsin that runs from an interchange at I-55 inNormal, Illinois, toState Trunk Highway 29 (WIS 29) approximately six miles (9.7 km) south ofWausau, Wisconsin.^[2][3] In total, Interstate 39 is 306.14 miles (492.68 km) long.^[1] In Illinois, the route has a total length of 140.82 miles (226.63 km);^[4] in Wisconsin, I-39 has a length of 182 miles (293 km).

Among the newest Interstate Highways in Illinois, I-39 was completed in 1992. Designed to replaceU.S. Route 51 (US 51) with anInterstate-grade freeway, the highwayruns concurrently withUS 20 inRockford before joining I-90. From Rockford toPortage, Wisconsin, I-39 and I-90 run concurrently. FromMadison to Portage, I-94 joins the two; at 29 miles (47 km), the three-way concurrency is the longest in the country. From Portage northward, US 51 rejoins I-39, and the Interstate uses its mileposts northward.

In Illinois, I-39 begins atI-55 north ofBloomington–Normal, Illinois, less than one mile east from the intersection of I-74 and I-55 that runs around the city of Normal. US 51 splits from I-55, joining I-39; exit 2 marks the northern terminus of theUS 51 business route. From Normal northward, I-39 runs northward largely through rural areas. At exit 8, the route forms the southern terminus ofIllinois Route 251 (IL 251), which was derived from the original routing of US 51.

InOglesby in centralLaSalle County, I-39 passes next toStarved Rock State Park, the busiest state park in Illinois. North of the park, it crosses theIllinois River over theAbraham Lincoln Memorial Bridge; at 1.3 miles (2.1 km) long, it is the longest bridge in the state.^[5] Just north of the river, I-39 passes between the cities ofLaSalle andPeru; as it intersectsI-80 andUS 6, it makes its southernmost connections with the Chicago region. North of I-80, the wind turbines of theMendota Hills Wind Farm (the first commercial wind farm in Illinois) can be seen from milepost 72 atMendota north to nearPaw Paw. As I-39 continues northward, I-39 also intersectsUS 52 andUS 30.

InOgle County, I-39 intersects withI-88 (IL 110), connecting I-39 to both Chicago and the Quad Cities regions. As it intersectsIL 38,IL 64, andIL 72, I-39 connects with the DeKalb–Sycamore region and far west suburbs of the Chicago area.

As I-39 crosses into Winnebago County, the Baxter Road exit (exit 115) is the final exit before I-39 joins theUS 20 freeway bypass in Rockford. Approximately a mile east of the Alpine Road/US 20 interchange, I-39 joins US 20, moving from nearly entirely farmland to medium-density populated areas.

After heading northeast for approximately four miles (6.4 km), US 20 splits from I-39/US 51; a mile northward, I-39/US 51 runs concurrently with I-90 (Jane Addams Memorial Tollway). Though signed as I-39/I-90, the concurrency follows the mileposts of I-90. Though I-39 itself is not tolled, theIllinois Tollway collects tolls on the I-90 portion, including two ramp interchanges and an open-road toll plaza between Rockton and South Beloit.

At exit 1 (IL 75) inSouth Beloit, US 51 splits from I-39 to join IL 75; two miles (3.2 km) westward, it continues the route of IL 251 into Wisconsin. For all but one mile that I-39 is in Illinois, it runs concurrently with US 51.

I-39 enters Wisconsin in Rock County, concurrently with I-90. Bypassing Beloit to the east, it passes underneath the County Trunk Highway P bridge (CTH-P, Stateline Road). The tri-stack exit 185 provides access to Beloit throughWIS 81 and serves as the southern terminus ofI-43 (accessing Milwaukee and Green Bay).^[6] The northernmost interchange serving the Beloit region is CTH-S (Shopiere Road) at exit 183. About seven miles (11 km) north of the I-43 interchange, I-39/I-90 is joined byWIS 11 for two miles (3.2 km) as it bypassesJanesville. In addition to the northern interchange that holds WIS 11, Janesville is also accessed byUS 14 andWIS 26 (Milton Avenue). After crossing theRock River, I-39/I-90 has an interchange withWIS 59, connecting it withEdgerton (to the west) andMilton (to the southeast).^[6]

I-39 entersDane County north of WIS 59, passing west ofLake Koshkonong. For approximately four miles (6.4 km), US 51 rejoins the Interstate (from mile 160 to 156) before it heads west throughStoughton. I-39/I-90 changes direction north ofUtica, gradually turning northwest. At exit 142, the highway turns returns north as it meetsUS 12/US 18 in Madison, forming the eastern terminus of the Madison Beltline Highway; for approximately 650 feet (200 m), northbound I-39 is reduced to two lanes (for the first time since Cherry Valley, Illinois). North of the Beltline, I-39 accesses Madison through an interchange withWIS 30 andI-94 (routed from Milwaukee); the interchange is known as the Badger Interchange.^[7] Two miles (3.2 km) further north, the highway has an interchange withUS 151 (splitting Madison andSun Prairie); the northernmost Madison-area I-39 interchanges are US 51 (Madison andDeForest) and WIS 19 (Sun Prairie andWaunakee); CTH-V (West North Street) for DeForest serves as the last Dane County exit.

I-39/I-90/I-94 entersColumbia County four miles (6.4 km) north-northwest of CTH-V.^[6] From the county line northward, the highway returns to rural surroundings. Three miles (4.8 km) after crossing theWisconsin River, exit 108 (Wisconsin Dells) splits I-90/I-94 from I-39. For the first time since the US 20 Bypass in Rockford–Cherry Valley, I-39 is four lanes instead of six or eight. I-39 continues northward fromWIS 78 (which terminates at the interchange), routed towards Portage. I-39 connects with Portage throughWIS 33, crosses the Wisconsin River a second time, connects withWIS 16; a third interchange rejoins I-39 with US 51. I-39 takes on the mileposts of the latter.

After taking on US 51, I-39 continues northward, with few directional changes throughMarquette County andWaushara County. InPortage County, the highway continues its northward direction until it reaches theStevens Point region, where it bypasses the city to the east and north; four interchanges connect with the city (CTH-HH,US 10/WIS 66, Stanley Street, and Bus. US 51).

From Stevens Point northward, I-39 largely parallels the path of the Wisconsin River and Lake DuBay. Following its entrance intoMarathon County,WIS 153 connects to I-39 inMosinee, adjacent to theCentral Wisconsin Airport. The final north-south interchange of I-39 is exit 185 (Bus. US 51) inRothschild, just before I-39 crosses the Wisconsin River.

I-39 ends with exit 187, asWIS 29 merges with US 51 (for approximately four miles [6.4 km]); the latter highway continues north to its terminus at US 2 at the Wisconsin–Michigan border.

When theInterstate Highway System was first being planned, Illinois made a request for a north–south highway fromSouth Beloit toSalem. 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-lanearterial road, experiencing many crashes and earning the nickname "Killer 51".^[8]

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 inRockford to I-57 just north of Salem, similar to the earlier requested route. Due to traffic counts, only the portion between Rockford andDecatur was prioritized.^[9]

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. TheIllinois Department of Transportation (IDOT) wanted the entire highway built toInterstate Highway standards, but a transportation committee established to review the proposed supplemental freeway system recommended only Interstate construction between Rockford andI-80.^[10] The highway fromOglesby south to Decatur was recommended to be an at-grade expressway, utilizing the existing road where possible. After a decade of lobbying by interest groups, it was announced in 1986 that US 51 would be rebuilt to Interstate standards from Oglesby toNormal.^[11] However, due to funding concerns and local opposition, it was decided that theBloomington to Decatur segment would not be built to Interstate standards; this segment was made a four-lane expressway.^[12]

The first segment of the freeway opened 1984 fromIL 5 (nowI-88) inRochelle, to US 20 in Rockford.^[13] 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.^[14] By December 1987, construction on the section of I-39 between I-80 andIL 251 was finished. The next section, between IL 251 andI-55 in Bloomington–Normal, was completed by 1992, although this stretch of the highway was opened in several phases as completed.^[15] In December 1989, the section from Bloomington–Normal to Hudson opened, a distance of about 4.4 miles (7.1 km).^[16] In early September 1992, another segment opened from IL 116 north to IL 17.^[17]

In Wisconsin, the highway was officially designated in 1992.^[18] In October 1993, theAmerican Association of State Highway and Transportation Officials (AASHTO) established part of I-39 in its northern section between Rockford andRib 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 theWisconsin Department of Transportation (WisDOT) had to reconstruct the interchange connecting I-90 and I-94 withWIS 78 nearPortage.^[19] Signs denoting I-39 were placed along the highway in Wisconsin until 1996, when the section between Portage and Rib Mountain (near Wausau) received its signs.^[18] This occurred after then–GovernorTommy Thompson designated the stretch between Portage and Wausau in 1996 after a five-year push to get the Interstate designation approved.^[19] The remaining segment along I-90/I-94 was not signed for I-39 until late 1998.^[18] 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.^[20] The designation of I-39 violated Wisconsin's rule of not having any state trunk highway number duplicated—Interstate, US, or state—asWIS 39 already existed.^[18]

State	County	Location	mi[21]	km	Exit[22]	Destinations	Notes
Illinois	McLean	Normal	0.00	0.00	—	I-55 /US 51 south toI-74 –Chicago,St. Louis,Decatur,Peoria,Champaign	Southern terminus of I-39; southern end of US 51 concurrency; I-55 exit 164;Central Illinois Regional Airport
			1.53	2.46	2	US 51 Bus. south (Main Street) –Bloomington,Normal
		Hudson	4.67	7.52	5	CR 12 (Franklin Street) –Hudson
		Hudson Township	7.75	12.47	8	IL 251 north /CR 8 (Lake Bloomington Road) –Kappa	Southern terminus of IL 251
	Woodford	El Paso	14.35	23.09	14	US 24 –Peoria,El Paso
		Woodford	22.37	36.00	22	IL 116 –Peoria,Pontiac
		Minonk	26.94	43.36	27	CR 2 –Minonk
	Marshall	Wenona	35.02	56.36	35	IL 17 –Lacon,Wenona
	LaSalle	Lostant	41.60	66.95	41	IL 18 –Henry,Streator
		Tonica	48.67	78.33	48	CR 54 (Reed Richardson Road) –Tonica
		Eden Township	51.70	83.20	51	IL 71 –Hennepin,Oglesby,Granville
			52.47	84.44	52	IL 251 –Peru,LaSalle
		Oglesby	53.79	86.57	54	Walnut Street –Oglesby
		Illinois River			Abraham Lincoln Memorial Bridge
		La Salle	56.75	91.33	57	US 6 (5th Street) –LaSalle,Peru,Ottawa
			58.68– 59.46	94.44– 95.69	59	I-80 –Chicago,Des Moines,LaSalle,Peru	Signed as exits 59A (east) and 59B (west); I-80 exit 79
		Troy Grove	66.16	106.47	66	US 52 –Troy Grove
		Mendota	72.09	116.02	72	US 34 –Mendota,Earlville
	Lee	Paw Paw	82.57	132.88	82	CR 10 (Chicago Road) –Paw Paw
		Willow Creek Township	87.34	140.56	87	US 30 –Sterling,Rock Falls,Aurora
		Steward	93.34	150.22	93	CR 2 (Perry Road) –Steward
	Ogle	Rochelle	97.10– 97.79	156.27– 157.38	97	I-88 Toll /IL 110 (CKC) (Ronald Reagan Memorial Tollway) –Moline,Rock Island,Chicago	Signed as exits 97A (east) and 97B (west); I-88 exit 78
			99.46	160.07	99	IL 38 /Lincoln Highway –DeKalb,Rochelle
		Lynnville Township	104.50	168.18	104	IL 64 –Sycamore,Oregon
		Monroe Center	110.98	178.60	111	IL 72 –Genoa,Byron,Kingston
	Winnebago	Rockford Township	115.49	185.86	115	CR 11 (Baxter Road)
		Rockford	119.05– 119.56	191.59– 192.41	118-119	US 20 west (Rockford Bypass) –Freeport	Southern end of US 20 concurrency;Chicago Rockford International Airport
		Cherry Valley	122.17	196.61	121	US 20 east (Harrison Avenue) –Belvidere	Northern end of US 20 concurrency; former cloverleaf interchange converted todiverging diamond interchange
			122.90	197.79	122	I-90 Toll east (Jane Addams Memorial Tollway) –Chicago	Southern end of I-90 concurrency; I-90 exit 17; I-39 uses I-90's exit numbers from here north
		Rockford	124.45	200.28	15	US 20 Bus. (State Street)	Last free exit northbound
			127.77	205.63	12	CR 55 west (East Riverside Boulevard)	Toll on northbound exit and southbound entrance
		Machesney Park	131.31	211.32	8	IL 173 (West Lane Road) –Machesney Park	Toll on northbound exit and southbound entrance
		Rockton	136.71	220.01	South Beloit Toll Plaza 1
		South Beloit	137.53	221.33	3	CR 9 (Rockton Road)	Last free exit southbound; northwestern end of Jane Addams Memorial Tollway
			139.93	225.20	1	US 51 north /IL 75 –South Beloit	Northern end of US 51 concurrency
			140.25 0.00	225.71 0.00	Illinois–Wisconsin state line
Wisconsin	Rock	Town of Turtle	2.48	3.99	185B	I-43 north –Milwaukee	I-43 exits 0A-B southbound; formercloverleaf interchange; undergoing conversion totri-stack interchange.
			2.46	3.96	185A	WIS 81 west (Milwaukee Avenue) –Beloit	Former cloverleaf interchange; undergoing conversion todiverging diamond interchange for access to/from 43 via County route X.
			4.78	7.69	183	CTH-S (Shopiere Road)
		Town of La Prairie	9.95	16.01	177	WIS 11 west (Avalon Road) –Janesville,Avalon	Southern end of WIS 11 concurrency;Southern Wisconsin Regional Airport
		Janesville	12.49	20.10	175	Alt. I-39 north / Alt. I-43 north (Racine Street) /WIS 11 east –Delavan	Northern end of WIS 11 concurrency; formerBus. US 14
			15.61– 15.66	25.12– 25.20	171B	Alt. I-39 south /US 14 –Janesville	Formerly split into exits 171B (west) and 171C (east)
			16.41	26.41	171A	WIS 26 –Milton
		Town of Fulton	24.62	39.62	163	WIS 59 –Edgerton,Milton,Whitewater
	Dane	Town of Albion	27.60	44.42	160	US 51 south /WIS 73 /WIS 106 –Edgerton,Deerfield	Southern end of US 51 concurrency
		Town of Christiana	31.30	50.37	156	US 51 north –Stoughton	Northern end of US 51 concurrency
		Town of Pleasant Springs	40.40	65.02	147	CTH-N –Stoughton,Cottage Grove
		Town of Blooming Grove	45.54	73.29	142	US 12 /US 18 (Beltline Highway) –Madison,Cambridge	Signed as exits 142A (west) and 142B (east); US 12 exit 267
		Madison	49.39	79.49	138B	WIS 30 west –Madison	Left exit and entrance northbound; servesDane County Airport; WIS 30 exit 3 eastbound and exit 240A westbound
			49.74	80.05	138A	I-94 east –Milwaukee	Left exit and entrance southbound; southern end of I-94 concurrency; I-94 exit 240
			51.74	83.27	135C	High Crossing Boulevard	Northbound exit and southbound entrance
			51.96– 52.00	83.62– 83.69	135B	US 151 north –Sun Prairie	Cloverleaf interchange
					135A	US 151 south –Madison
		Town of Burke	55.20	88.84	132	US 51 (Stoughton Road) –Madison,De Forest
		Community of Windsor	56.68	91.22	131	WIS 19 –Waunakee,Sun Prairie
		Town of Vienna	60.93	98.06	126	CTH-V –Dane,De Forest
	Columbia	Town of Arlington	67.97	109.39	119	WIS 60 –Lodi,Arlington,Columbus
		Town of Dekorra	71.99	115.86	115	CTH-CS –Poynette,Lake Wisconsin
		Town of Caledonia	78.63	126.54	—	I-90 west /I-94 west –Wisconsin Dells	Northern end of I-90/I-94 concurrency; I-90 exit 108B
			79.26	127.56	84	WIS 78 south –Merrimac	Signed as exit 108A northbound
			79.73	128.31	85	Cascade Mountain Road
		Portage	81.73	131.53	87	WIS 33 (Cook Street) –Portage,Baraboo
			84.13	135.39	89	WIS 16 (Wisconsin Street) toWIS 127 –Portage,Wisconsin Dells,Columbus	Signed as exits 89A (east) and 89B (west) northbound
		Town of Fort Winnebago	85.79	138.07	92	US 51 south (New Pinery Road) –Portage	Southern end of US 51 concurrency; exit numbers from here north based on US 51's mileposts
	Marquette	Town of Moundville	94.43	151.97	100	WIS 23 west / CTH-P –Wisconsin Dells,Endeavor	Southern end of WIS 23 concurrency
		Town of Oxford	98.61	158.70	104	CTH-D –Packwaukee	Northbound exit and southbound entrance
			100.77	162.17	106	WIS 23 east /WIS 82 west –Oxford,Montello,Princeton,Packwaukee	Northern end of WIS 23 concurrency
		Westfield	107.32	172.71	113	CTH-E / CTH-J –Westfield,Harrisville,Princeton
	Waushara	Coloma	118.29	190.37	124	WIS 21 –Coloma,Necedah,Wautoma,Oshkosh,Tomah
		Town of Hancock	125.35	201.73	131	CTH-V –Hancock
		Town of Plainfield	130.94	210.73	136	WIS 73 –Plainfield,Wisconsin Rapids,Wautoma,Nekoosa
	Portage	Town of Pine Grove	134.07	215.76	139	CTH-D –Almond
			137.56	221.38	143	CTH-W –Bancroft,Wisconsin Rapids
		Town of Plover	145.91	234.82	151	WIS 54 (Post Road) /Bus. US 51 –Wisconsin Rapids,Plover,Waupaca
		Village of Plover	147.51	237.39	153	CTH-B (Plover Road) –Wisconsin Rapids,Plover,Amherst
			150.53	242.25	156	CTH-HH (McDill Avenue) –Whiting,Stevens Point
		Stevens Point	152.71	245.76	158	US 10 east /WIS 66 west (Main Street) –Stevens Point,Waupaca,Appleton,Marshfield	Southern end of US 10 concurrency; southern end of WI 66 concurrency; signed as exits 158A (east) and 158B (west) northbound
			153.94	247.74	159	WIS 66 east (Stanley Street) –Stevens Point,Rosholt	Northern end of WI 66 concurrency
			155.76	250.67	161	Bus. US 51 (Division Street) –Stevens Point
		Hull	157.63	253.68	163	Casimir Road	To CTH-X
			159.75	257.09	165	US 10 west –Marshfield	Northern end of US 10 concurrency
						CTH-X	Former diamond interchange; removed for construction of US 10 exit
		Town of Dewey	165.39	266.17	171	CTH-DB –Knowlton,Lake DuBay
	Marathon	Town of Knowlton	169.64	273.01	175	WIS 34 (Balsam Road) –Knowlton,Wisconsin Rapids
		Mosinee	173.57	279.33	179	WIS 153 –Mosinee,Elderon	Central Wisconsin Airport
		Kronenwetter	175.39	282.26	181	Maple Ridge Road
		Rothschild	179.52	288.91	185	Bus. US 51 –Rothschild,Kronenwetter
		Village of Rib Mountain	182.14	293.13	187	WIS 29 east –Weston,Green Bay US 51 north /WIS 29 west –Wausau,Chippewa Falls	Northern terminus;[23] northern end of US 51 concurrency; freeway continues as US 51/WIS 29
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       Electronic toll collection       Incomplete access

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• Illinois Highway Ends: Interstate 39

• Interstate 39
• Interstate Highway System
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• Transportation in McLean County, Illinois
• Transportation in Woodford County, Illinois
• Transportation in Marshall County, Illinois
• Transportation in LaSalle County, Illinois
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• Transportation in Ogle County, Illinois
• Transportation in Winnebago County, Illinois
• Transportation in Rock County, Wisconsin
• Transportation in Dane County, Wisconsin
• Transportation in Columbia County, Wisconsin
• Transportation in Marquette County, Wisconsin
• Transportation in Waushara County, Wisconsin
• Transportation in Portage County, Wisconsin
• Transportation in Marathon County, Wisconsin

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