Interstate 39 in Wisconsin


Begin reward
End Rhinelander
Length 182 mi
Length 293 km
  • Illinois185 → Milwaukee
  • 183 reward
  • 177 South Janesville
  • 175 Janesville
  • 171 Janesville
  • 163 Newville
  • 160 Edgerton
  • 156 Stoughton
  • 147 Cottage Grove
  • 142 → Madison
  • 138 → Milwaukee
  • 135 → Madison
  • 132 Madison
  • 131 Windsor
  • 126 Deforest
  • 119 Arlington
  • 115 Poynette
  • 108 → Minneapolis
  • 85 Cascade Mountain Road
  • 87 Portage
  • 90 Portage
  • 92 North Portage
  • 100 Endeavor
  • 104 Packwaukee
  • 106 Oxford
  • 113 Westfield
  • 124 Dove
  • 131 Hancock
  • 136 Plainfield
  • 139 Almond
  • 143 Bancroft
  • 151 Plover
  • 153 Plover
  • 156 Whiting
  • 158 Stevens Point
  • 159 Stevens Point
  • 161 Stevens Point
  • 163 Casimir
  • 165 → Marshfield
  • 171 Lake Du Bay
  • 175 Knowlton
  • 179 Central Wisconsin Airport
  • 181 Mosinee
  • 185 Evergreen
  • 187 → Green Bay
  • 190 Wausau
  • 191 Marathon City
  • 192 Wausau
  • 193 North Wausau
  • 194 North Wausau
  • 197 Brokaw
  • 205 County Road Q
  • 208 Merrill
  • 211 Merrill

Interstate 39 or I -39 is an Interstate Highway in the U.S. state of Wisconsin. The highway runs from the Illinois border at Beloit via the capital Madison to Merrill in the north of the state. The road is characterized by the double numbering, with I-90 and even triple with I-94 as well. The highway is 293 kilometers long.

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Travel directions

The split of I-39 and I-90/94 at Portage.

The end of I-39 at Wausau.

Near the town of Beloit, Interstate 39 in Illinois enters Wisconsin from Rockford, along with Interstate 90. After just a few miles, Interstate 43 turns off, which leads to Milwaukee and Green Bay. Then I-39 and I-90 pass through the town of Janesville, where they intersect with US 14, which runs inland from Chicago to Madison. One then reaches Madison, the capital of Wisconsin. The city has 223,000 inhabitants, with a conurbation that is twice as large, built around and between two lakes. On the east side of Madison, Interstate 94, which comes in from Milwaukee, merges into triple-numbering.

You then cross the US 151, the highway from Madison to Fond du Lac. You then pass through a fairly flat area, which mainly consists of agricultural fields. The double numbering lasts about 50 kilometers. At Portage, I-39 exits as Interstate 90 and Interstate 94 veer west toward Minneapolis. It then crosses the Wisconsin River, passing the town of Portage.

Then the route to the north begins, which is double-numbered with US 51. This road used to be only US 51. Since this is not a through route, the road is fairly quiet. The landscape is quite monotonous. One does not encounter large places. Near the town of Stevens Point, you cross the US 10, which runs from Appleton to Saint Paul. You then pass Wausau, the last larger town along the highway. Here one crosses SR-29, a fairly important State Route, which runs from Green Bay to Eau Claire, both fairly large places in Wisconsin. This is where I-39 officially ends, but the highway continues to Merrill, and on to Rhinelander. There, the highway becomes US 51, which leads to Ironwood on the Michigan border.

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The highway existed before the number I-39 was assigned. This happened in 1992, but the portion south of Portage was not signposted as I-39 until 1998. The road was previously numbered US 51. The last part of this was developed as a freeway between Endeavor and Coloma in the late 1980s or early 1990s.

On October 24, 2016, a diverging diamond interchange opened at Exit 177 just south of Janesville. This was the first DDI in Wisconsin. On November 12, 2019, a 20-mile widening to 2×3 lanes was completed between Edgerton and Madison. In 2020, a widening to 2×3 lanes was completed between Janesville and Edgerton. The final section between Beloit and Janesville was completed on December 3, 2021.

Traffic intensities

I-39/90 at Madison.

Madison has about 85,000 vehicles per day, the busiest section of I-39. This section is already double numbered with I-90. After merging I-94, the intensity is between 63,000 and 71,000 vehicles per day. North of Portage, when I-39 runs alone again, the intensity quickly drops to 22,000 vehicles.

Lane Configuration

Van Unpleasant Lanes Comments
Exit 185 Exit 108 2×3 double numbered with I-90 and I-94
Exit 84 Exit 187 2×2

Interstate 39 in Wisconsin