Interstate 39

Interstate 39 Illinois
I-39-90 south / I-94 east split - Madison, WI

I-39 south / I-90 east separate with Interstate 94 on the east side of Madison, Wisconsin. I-94 bee lines for Milwaukee while I-39/90 remain paired south to Beloit and Rockford, Illinois. 05/30/11


Interstate 39 runs northward through Illinois and Wisconsin as a long distance bypass for traffic around the Chicago and Milwaukee metropolitan areas. A mostly rural route, I-39 begins on the north side of Normal at I-55, overtaking U.S. 51 to Peru and La Salle, where it meets Interstate 80. North from there, the freeway continues to I-88 outside Rochelle and U.S. 20 on the south side of Rockford.

U.S. 20 turns I-39 east to Interstate 90, the Jane Addams Memorial (Northwest) Tollway. I-39/90 combine there along the east side of Rockford to Beloit, Wisconsin, where they meet the south end of Interstate 43. Advancing northward, the pair pass through Janesville while en route to the capital city of Madison. There Interstate 94 ties in from Waukesha and Milwaukee to the east to form the longest three way overlap on the Interstate system.

I-39, I-90 and I-94 run concurrently for 29 miles along a northward heading from Madison to the outskirts of Portage. I-39 separates with I-90/94 just beyond the Wisconsin River to again overtake U.S. 51 northward from Portage to Packawaukee, Plover and Stevens Point.

U.S. 10 combines with I-39/U.S. 51 from Stevens Point to a freeway completed in August 2012 leading west to Junction City and Milladore. U.S. 51 parallels the Wisconsin River north to Mosinee, Rothschild and Wis 29, where Interstate 39 concludes. U.S. 51 extends the freeway along side Wis 29 west to Wausau and as a solo route northward to Merrill.

Parallel U.S. Routes

Interstate 39 overlays or parallels U.S. 51 for nearly its entire length. With the exception of the segment between I-90/94 and U.S. 51 at Portage, Interstate 39 runs concurrent with at least one other route for all 306 miles.

Route Information

  • North End – Wausau, WI

  • South End – Normal, IL

  • Branch Routes – 0

  • Total Mileage – 306.14


Illinois – 123.42

  • Cities – Normal, La Salle, Mendota, Rockford

  • JunctionsI-55 I-80 I-88 I-90

Wisconsin – 182.72

  • Cities – Beloit, Janesville, Madison, Portage, Plover/Stevens Point, Wausau

  • JunctionsI-43 I-94 I-90

Source: December 31, 2021 Interstate Route Log and Finders List

Northwest Illinois - 1986
Interstate 39 was complete between I-80 near La Salle and I-90 at Rockford. 1986 Gousha North American Road Atlas.

I-39 was extended south from I-80 to Oglesby in early 1989. The freeway was first envisioned in 1945 as a high speed route between Salem and South Beloit.8


The Illinois Department of Transportation (IDOT) applied for the designation of Interstate 39 to the American Association of State Highway and Transportation Officials (AASHTO) on October 22, 1984:

The freeway in the U.S. Route 51 corridor from Rockford south to Illinois Route 5 is built to Interstate standards. The segment south of Illinois Route 5 to Interstate Route 80, presently under construction, also meets Interstate standards. Therefore, we are proposing that this 64 mile segment of freeway between FAI 90 at Cherry Valley and FAI 80 at LaSalle/Peru, be designated as Interstate Route 39 under Title 23 U.S.C. 139(b). This route would provide a direct connection between Interstate Route 80 and Interstate Route 90 and would serve the Rockford Metropolitan area which as a population of over 200,000.

AASHTO disapproved the application on December 8, 1984, instead recommending a three digit spur. However after reconsideration, the Route Numbering Committee approved a subsequent request by IDOT on January 3, 1985 for the establishment of I-39 in a letter dated February 5, 1985.

When proposed in 1984 as I-39, the freeway along U.S. 51 was only constructed between former IL 5 (East-West Tollway/I-88) and U.S. 20 at Rockford. The section between IL 5 and Interstate 80 opened in 1986.

AASHTO approved an extension of Interstate 39 south from I-80 at LaSalle/Peru to I-55 at Bloomington subject to Federal Highway Administration (FHWA) concurrence on June 10, 1986. This section initially opened to traffic from I-80 south across the Illinois River to IL 251 (old U.S. 51) in December 1987. The remainder of I-39 south between IL 251 and Bloomington-Normal was constructed between 1987 and 1992.

I-39 north crossing the Abraham Lincoln Memorial Bridge north from Oglesby, IL.

Interstate 39 spans the Illinois River north across the Abraham Lincoln Memorial Bridge to LaSalle, Illinois. 08/10/09

Separate applications by IDOT and the Wisconsin Department of Transportation (WisDOT) for the northward extension of Interstate 39 from Rockford, Illinois to STH 29 in Wausau, Wisconsin were approved by AASHTO on October 22, 1993. The IDOT application added 19 miles from I-90 near Rockford to the Wisconsin state line. The WisDOT application cited the addition of 182 miles for I-39 in the state, with 103 miles independent of another Interstate highway.

The full installation of signs acknowledging I-39 along the overlap with I-90 and I-94 in southern Wisconsin was a slow process. The mainline was well posted with reassurance markers, but intersecting roads generally omitted the I-39 designation until at least 2003. One signing oddity was made in the city of Madison, where instead of signing I-39/90/ 94 with three separate signs, a single blank Interstate shield was used instead. These trailblazers were posted near East Towne Mall, which is located southwest of the interchange joining U.S. 151 with I-39/90/94.1

Construction on Interstate 39 was initiated in the late 1970s and early 1980s. The following chronology shows the construction time line of I-39, including information provided by Steve Sarver and Robb Haukohl:2

  • 1984 – Interstate 39 opened from U.S. 20 near Rockford to IL 5 near Rochelle.
  • 1986 – Interstate 39 extended from IL 5 to I-80.
  • December 1987 – the section from Interstate 80 south across the Illinois River was opened and its southern terminus was IL 251 (old U.S. 51). It was not open from IL 251 to IL 71. Named the Abraham Lincoln Memorial Bridge, the one mile long crossing is the longest span in Illinois.
  • Late 1988 – construction began on the interchange with Interstate 55 in Bloomington
  • Summer of 1990 – Interstate 55 was reconstructed around Normal with an additional lane of traffic. The existing interchange joining U.S. 51 and I-55 was closed completely and then reconstructed with its present configuration. Bridge work continued for the overpasses between Normal and Oglesby. The section from Oglesby to Normal utilizes a unique style of overpass construction that allowed for the elimination of the center pier. U.S. 51 was rerouted onto the I-55/74 bypass around Bloomington-Normal, and the main route town was designated as U.S. 51 Business (AASHTO action taken established U.S. 51 Business on June 2, 1990).
  • Summer/Fall of 1991 – segments of the new highway were opened south to IL 18.
  • May 29, 1992 – 4.4 miles of I-39 opened between Hudson and Kappa.
  • October 31, 19923 – final segment of Interstate 39 opened, completing the entire freeway from Rockford to Bloomington. IL 251 extends on most of the old U.S. 51; some minor rerouting was necessary because the new four-lane highway was built directly on top of the previous two lane road. IL 251 concludes at I-39, 7.5 miles north of Normal, while the four lane U.S. 51 Business was constructed over old U.S. 51 for 1.75 miles beyond Normal. There is a no section old old U.S. 51 in tact between the two routes.
  • Mid-1995 – The Willow Creek Rest Areas opened on both sides of Interstate 39 between Exit 82 and Exit 87. Grading for their ramp system was completed some time before the facilities were built. Also, before the rest areas opened, weigh stations operated along on both sides of the freeway, 17 miles to the north. These were later closed and fenced off to prevent access.
  • 1998-1999 – Interstate 39 extended northward into Wisconsin. Signage was placed first on the U.S. 51 freeway from Portage north to Wausau, and eventually along the overlap with I-90/94. The 1999 Rand McNally North American Road Atlas was the first to show Interstate 39 along in the Badger State.
  • 2003-2004 – Toll collection at the Cherry Valley Interchange in Rockford, where I-39 separates from I-90, was eliminated for southbound. Tolling along I-39 northbound at the exchange ceased in November 2004.
  • April 17, 2003 – E.J. ‘Zeke’ Giorgi Highway designated along Interstate 39 between I-88 (Ronald Reagan East-West Tollway) and the Illinois-Wisconsin State Line. Representative Zeke Giorgi pushed for the construction of I-39 through Northern Illinois.4

An extension of Interstate 39 north from Wausau to Merrill along U.S. 51 remains a possibility. Craig Holl wrote WisDOT to determine whether plans called for upgrading this stretch of U.S. 51 into I-39. Douglas Ross responded in October 2002,

The DOT is currently using design standards that will satisfy requirements for an Interstate Highway, to develop plans for the reconstruction of the segment of USH 51/ STH 29 between Fox Glove Road and Bridge Street. To the best of my knowledge, the Department has no plans at this time to formally request that I-39 be extended; however, if the request is made in the future this segment of roadway should meet the design standard requirements after the reconstruction is completed.

Started in 2004, a major project upgraded the freeway along U.S. 51 around Wausau to Interstate standards.5


Costing $291 million, the US 51/WIS 29 project reconstructed seven miles of U.S. 51 and Wis 29 between Foxglove Road and Bridge Street in Marathon County. The road was rebuilt into a six lane freeway between the east and west interchanges with STH-29, with auxiliary lanes added as well. Work also included a revamp of the east and west U.S. 51 connection with STH-29 into high speed systems interchanges. The east interchange was completed in 2006 and three of the four ramps at the west interchange were open to traffic in 2008. Overall construction was completed in 2010.6

The Cherry Valley Interchange project reconstructed the connection between Interstate 90 (Jane Addams Memorial Tollway) and I-39 in Rockford. The project started in 2008 and was completed on November 13, 2010. This work upgraded the trumpet interchange built in 1972 joining I-39/90 to utilize high speed ramps in all directions.7 An additional project widened the Tollway from Exit 3 (Rockton Road) to U.S. 20 Business (State Street) between 2007 and November 24, 2009.8

Major Projects

A long term project underway in south central Wisconsin, the I-39/90 Expansion Project, affected 45 miles of 1960s-era freeway along the I-39/90 overlap from the Illinois state line to U.S. 12/18 at Madison. Upgrades to the corridor included expansion of the freeway mainline to six overall lanes, reconfiguring 11 interchanges with substandard design elements, and additional expansion of I-39/90 to eight lanes from Wis 11 (Avalon Road) north to Wis 26. Construction ran from 2015 to 2021.10

The conversion of Exit 177 with Wis (Avalon Road) to a diverging diamond interchange created the first DDI in the state. Part of the South Segment at Beloit, a major upgrade started in Summer 2019 at the exchange joining I-39/90 with the south end of Interstate 43 and Wis 81. Work through Fall 2021 converted the previous cloverleaf interchange into a directional T for freeway to freeway movements and a DDI for Wis 81 leading west into Beloit.10

Photo Guides

North End US-51 Wis 29 – Wausau, Wisconsin

I-39 US 51 North at Wis 29

I-39/US 51 north at Wis 29 - Rib Mountain

One mile south of the three-wye interchange (Exit 187) with Wis 29 east. Wis 29 joins U.S. 51 north to the city of Wausau before resuming a westward heading to Chippewa Falls. 06/15/15

I-39/US 51 north at Wis 29 - Rib Mountain

An end shield for Interstate 39 appears just ahead of Exit 187 to Wis 29 east to nearby Schofield and Weston. 06/15/15

I-39/US 51 north at Wis 29 - Rib Mountain

Wis 29 ventures east along an expressway to Shawano, Green Bay and Interstate 41. U.S. 51 north / Wis 29 west overlap for 3.3 miles along an Interstate standard freeway to the west of Lake Wassau. 06/15/15

Wis 29 West at I-39 US 51

Wis 29 west at I-39/US 51 - Rothschild

Interstate 39 appears for the first time along the Wis 29 freeway west, two miles out at the Alderson Road overpass in the village of Rothschild. 08/14/09

Wis 29 west at I-39/US 51 - Rothschild

Wis 29 leads away from U.S. 51 Business and spans the Wisconsin River on the one-mile approach to Exit 170 with Interstate 39 south and U.S. 51. 08/14/09

Wis 29 west at I-39/US 51 - Rothschild

An $18.8 million project was underway between April 29, 2014 and May 25, 2017 that both widened and replaced the bridge deck over the Wisconsin River.9 06/15/15

Wis 29 west at I-39/US 51 - Rothschild

Beyond the Wisconsin River, Wis 29 expands to three lanes ahead of Left Exit 170 for I-39/U.S. 51 south to Stevens Point and Madison. 06/15/15

Wis 29 west at I-39/US 51 - Rib Mountain

The three-wye interchange (Exit 170) between Wis 29, I-39 and U.S. 51 replaced a trumpet interchange. Grading from some of the original ramps remains visible both to the north and west of the exchange. 06/15/15

US 51 South Wis 29 East at I-39

US 51/Wis 29 south at I-39 - Rib Mountain

Wis 29 east combines with the U.S. 51 freeway leading south into the town of Rib Mountain. The two routes part ways at Exit 187 where Interstate 39 begins. 06/15/15

US 51/Wis 29 south at I-39 - Rib Mountain

The entrance ramp from Rib Mountain Road forms an auxiliary lane southward to Exit 187 taking Wis 29 east to Weston. Wis 29 is a freeway from I-39/U.S. 51 east to Ringle, and an expressway with a 65 mile per hour speed limit to Green Bay. 06/15/15

US 51/Wis 29 south at I-39 - Rib Mountain

Interstate 39 commences at the separation of Wis 29 east from U.S. 51 south. I-39 parallels the Wisconsin River southward as a rural freeway to Stevens Point, where it combines with U.S. 10. 06/15/15

I-39 US 51 South

I-39/US 51 south of Wis 29 - Rib Mountain

The first confirming marker for Interstate 39 stands by milepost 186.8 ahead of the Foxglove Road overpass. 08/14/09

I-39 North End Throwback

I-39 US 51 North at Wis 29

I-39/US 51 north of Maple Ridge Rd - Kronenwetter, WI

The last I-39/U.S. 51 north reassurance shield assembly was previously this assembly posted beyond Maple Ridge Road near Milepost 182. Photo by Jay Maynard (12/25/02).

I-39/US 51 north at Wis 29 - 2002

Removed by 2007, this guide sign north of Exit 185 marked the transition of I-39/U.S. 51 into just U.S. 51. Photo by Jay Maynard (12/25/02).

I-39/US 51 north at Wis 29 - 2002

I-39/U.S. 51 north at Wis 29 east before the interchange at Exit 187 was reconfigured from a trumpet into a three-wye. Photo by Jay Maynard (12/25/02).

US 51 South at I-39

US 51 south at US 51 Business/CTH K - 2002

The first sign referencing Interstate 39 on U.S. 51 south preceded the exchange with CTH K north and U.S. 51 Business south at Exit 195. Subsequent road work replaced the substandard overpasses in the Wausau area. Photo by Jay Maynard (12/25/02).

US 51 south at I-39 and STH 29 - 2002

The south split of U.S. 51 and Wis 29 when a trumpet interchange joined the two freeways. Photo by Jay Maynard (12/25/02).

I-39/US 51 south of US 51 Business - Rothschild, WI

The first confirming marker for I-39 south was previously posted at Milepost 185, beyond the folded diamond interchange with U.S. 51 Business for the Wausau suburbs of Rothschild and Schofield. Photo by Jay Maynard (12/25/02).

South End I-55 US-51 – Bloomington, Illinois

I-39 US 51 South at I-55

I-39/US 51 south at I-55 - Normal, IL

U.S. 51 Business branches east from I-39/U.S. 51, one mile north of Interstate 55 at Normal. 05/06/18

I-39/US 51 south at I-55 - Normal, IL

Interstate 55 encircles north side of Normal east to Business Loop I-55 (Historic U.S. 66) and west along side I-74 and U.S. 51 to Bloomington. 05/06/18

I-39/US 51 south at I-55 - Normal, IL

The final confirming marker for Interstate 39 south stands just ahead of the E 1800 North Road underpass. 05/06/18

I-39/US 51 south at I-55 - Normal, IL

Southbound I-39 partitions with the left exit for Interstate 55 northeast toward Chicago. The mainline defaults onto I-55 south, which combines with I-74 eastbound nearby. 05/06/18

I-39/US 51 south at I-55 - Normal, IL

An end shield appears along the ramp to I-55/U.S. 51 south toward St. Louis and Decatur. 05/06/18

I-55 US 51 North at I-39

I-55/74-US 51 north at I-39 - Normal, IL
I-55/74-US 51 north at I-39 - Normal, IL

Back to back trumpet interchanges connect Interstate 55 with I-74 west to Peoria and I-39 north to Rockford. 05/07/18

I-55/US 51 north at I-39 - Normal, IL
I-55/US 51 north at I-39 - Normal, IL

The entrance ramp from I-74 east to I-55/U.S. 51 north adds an auxiliary lane to Exit 164 with Interstate 39 north. 05/07/18

I-39 US 51 North

I-39/US 51 north after I-55 - Normal, IL

Interstate 39/U.S. 51 north lead away from Normal across agricultural areas to Hudson. 05/07/10

I-39/US 51 north after I-55 - Normal, IL

Advancing north toward the end of U.S. 51 Business, motorists pass by the first reassurance shield for I-39. Photo by Peter Johnson (06/19/19).

I-39 South End Throwback

I-39 US 51 South at I-55

I-39/US 51 south at I-55 - 2001

Replaced button copy signs at the south end of Interstate 39. Photo by Jeff Royston (11/25/01).

I-55 US 51 North at I-39

I-55-74/US 51 north at I-39 - 2002

Sign bridge replacements made by 2008 along Interstate 55 around Normal included this assembly two miles south of I-39. Photo by Brian Dowd (06/02).

I-55-74/US 51 north at I-39 - 2002

Interstate 74 splits with I-55/U.S. 51 north via a single lane ramp for its continuation west to Peoria and the Quad Cities. I-55 curves northeast one mile to the south end of Interstate 39. This sign bridge was also replaced by 2008. Photo by Brian Dowd (06/02).

I-55/US 51 north at I-39 - 2002

These button copy signs were removed by 2008. A single overhead for I-39/U.S. 51 north to Rockford was added in place. Photo by Brian Dowd (06/02).

I-55/US 51 north at I-39 - 2002

U.S. 51 combines with I-39 north 124 miles to their merge with I-90 (Jane Addams Memorial Tollway) in Rockford. Photo by Brian Dowd (08/16/02).

I-55 South at I-39 US 51

I-55 south at I-39/US 51 - 2002

Interstate 55 turns west beyond the split with Business Loop I-55 (Veterans Parkway) and runs along side Ironwood Golf Course ahead of I-39. Photo by Brian Dowd (06/02).

I-55 south at I-39/US 51 - 2002

A collector distributor separates from the I-55 southbound mainline for both U.S. 51 Business (Main Street) to Normal and I-39/U.S. 51 north to Rockford. Photo by Brian Dowd (06/02).

I-55 south at I-39/US 51 - 2001

Former button copy overheads posted ahead of the Linden Street underpass and the folded diamond interchange (Exit 165) with U.S. 51 Business (Main Street). Photo by Jeff Royston (11/25/01).

I-55 south at I-39/US 51 - 2001

Exit 164 departs from I-55 south for I-39/U.S. 51 north to Peru, La Salle and Rockford. U.S. 51 south overlaps with I-55 and I-74 to the west side of Bloomington. Photo by Jeff Royston (11/25/01).

I-39 US 51 North

I-39/US 51 north after I-55 - 2001

A state named shield for Interstate 39 was previously posted north of the E 1800 North Road underpass. Photo by Jeff Royston (11/25/01).


  1. Chris Lokken, personal email (“Some information on Wisconsin’s interstates”), Friday, April 7, 2006 and May 11, 2006.
  2. Robb Haukohl, personal email (“I-39 Updates”), Wednesday, March 30, 2005.
  3. “Completion of last link ends the 47-year-old saga of I-39” Pantagraph, The (Bloomington, IL), October 31, 1992.
  4. “Madigan to dedicate Giorgi Highway today.” Rockford Register-Star (IL), April 17, 2003.
  5. Eric Conn, personal email (“Wisconsin 29”), Tuesday, November 30, 2004.
  6. US 51/WIS 29 project, WisDOT project web site.
  7. “I-90/39 Ramp Project.”, July 23, 2010.
  8. “Jane Addams Memorial Tollway – Newburg Road to Rockton Road – Reconstruct & Widen” Illinois Tollway, press release, November 24, 2009.
  9. 511 Wisconsin Construction Projects – October 22, 2015 Weekly Construction Update. North Central Region, Weekly Updates.
  10. I-39/90 Expansion Project, Project Overview. Wisconsin Department of Transportation.

Page updated April 12, 2023.