US 41 Interstate Conversion

US 41 conversion logo

​This study is complete and this website is for archive purpose only.

US 41 officially was added to the interstate system in April of 2015.

From the Wisconsin state line to Green Bay, in Kenosha, Racine, Milwaukee, Waukesha, Washington, Dodge, Fond du Lac, Winnebago, Outagamie, and Brown counties.

News release, Dec. 15, 2014 - Federal legislation will enable converting US 41 to an interstate

US 41 Interstate Conversion project location

Project location

  • The study corridor is 175 miles long and located almost entirely within the state of Wisconsin.
  • The interstate will begin at the I-94/US 41 interchange located approximately one mile south of the Wisconsin/Illinois border.
  • The route continues north concurrently with I-94 to the Mitchell interchange and then northwesterly concurrent with I-894 to the Zoo interchange.
  • From the Zoo interchange, the route will extend north along US 45 and US 41 through Fond du Lac, the Fox Valley, and Green Bay and end at the I-43 interchange.
  • Communities along the corridor include: Pleasant Prairie, Kenosha, Racine, Oak Creek, Franklin, Greenfield, Milwaukee, West Allis, Wauwatosa, Menomonee Falls, Germantown, Slinger, Lomira, Fond du Lac, Oshkosh, Neenah, Menasha, Grand Chute, Appleton, Little Chute, Kaukauna, De Pere, Ashwaubenon, Howard and Green Bay.

Project overview 

In 2005, 142 miles of US 41 from Milwaukee to Green Bay were identified by the federal government for inclusion in the U.S. Interstate Highway System.                                                        

SAFETEA-LU legislation initially identified the south terminus as the Mitchell Interchange (I-94/I-894) in Milwaukee. However, the Interstate Conversion study team elected to extend the corridor concurrent with I-94 south approximately 33 miles to the I-94/US 41 interchange for a number of reasons, including:

  • It links Wisconsin metropolitan areas and markets to the greater Chicago metropolitan area. Chicago is the economic epicenter of the entire Midwest and a key hub near the end of the corridor.
  • With the extension into Illinois, the interstate route becomes a true interstate route with a total length of 175 miles.
  • The extension will allow the signing for the cardinal direction to be north/south rather than the current east/west signing. A long-term goal of reducing driver confusion when driving north on a roadway signed as “west” can be realized for the northern Illinois and southern Wisconsin areas.

Designating the highway as an Interstate is expected to bring economic growth, increase the safety of the road, create a corridor identity and bring broader benefits to the state of Wisconsin.

Planning for the Interstate conversion began in 2007, with a long-term planning study finished in 2014. In fall of 2012, AASHTO approved the I-41 route number designation conditional upon subsequent approval by FHWA. FHWA approved the Formal Conversion Request Package and I-41 was added to the Interstate Highway System on April 7, 2015.

Project benefits

Designating the highway as an Interstate is expected to:

  • Bring economic growth along the newly designated corridor
  • Increase the safety of the road for people and vehicles
  • Create a corridor identity
  • Bring broader benefits to the state of Wisconsin