Interstate 41 (I-41) is a north–south Interstate Highway connecting the interchange of I-94 and U.S. Route 41 (US 41), located south of the Wisconsin–Illinois border at the end of the Tri-State Tollway in metropolitan Chicago, to an interchange with I-43 in metropolitan Green Bay, Wisconsin. The designation travels concurrently with US 41, I-894, US 45, I-43, and sections of I-94 in Wisconsin and Illinois. The route was officially added to the Interstate Highway System on April 7, 2015, and connects Milwaukee and Green Bay with the Fox Cities. Route description I-41 begins at the I-94/US 41 interchange in Russell, Illinois, located south of the Wisconsin–Illinois border at the end of the Tri-State Tollway. The highway continues north concurrently with I-94 as part of the North-South Freeway to the Mitchell Interchange in Milwaukee, turns west to run concurrently with I-894 and I-43 as the Airport Freeway to the Hale Interchange (forming a brief wrong-way concurrency with I-43), and turns north to run concurrently as the Zoo Freeway with I-894 and US 45 to the Zoo Interchange, with the US 45 concurrency continuing until the I-41/US 41/US 45 split near Richfield. The Interstate roughly parallels I-43, which runs north–south along Lake Michigan from Milwaukee to Green Bay. I-41 runs through the Fox Valley (including the cities of Fond du Lac, Oshkosh, and Appleton, along with the Fox Cities). At Appleton, I-41 intersects US 10 and State Trunk Highway 441 (WIS 441), the latter of which is a freeway that runs into the city and back to I-41. Further north, I-41 intersects WIS 172 on the south side of Green Bay, before running along the city's west side to its end at the I-43 interchange. The Interstate is approximately long and located almost entirely within the state of Wisconsin and is completely concurrent with a slightly adjusted alignment of US 41 to its termination in Green Bay. History The freeway portion of US 41 and US 45 from Milwaukee through the Fox Valley to Green Bay was proposed and designated as an Interstate Highway as part of the 2005 highway funding bill (Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users). In the initial language of the bill, the route was named Interstate 41, which correlates with the U.S. Highway it parallels and also complies with the Interstate naming guidelines through the American Association of State Highway and Transportation Officials (AASHTO).