I am originally from Milwaukee and admittedly had not explored the state of Wisconsin to it's full extent until the last few years. I decided to turn my UP trip into a Wisconsin State Park trip. These state parks are between a 5-6 hour drive from Milwaukee but are definitely worth a trip.
Copper Falls State Park
Copper Falls State Park is located in Mellen, Wisconsin. It spans over 3,000 acres and has approximately 17 miles of hiking trails. The Doughboy Nature Trail is the one that will bring you to the best waterfall views - unfortunately this trail is not dog friendly. Kona and I took a hike on the Red Granite Falls trail instead.
Amnicon Falls State Park
Further west, you will find Amnicon Falls State Park, located in South Range, Wisconsin. The park sits along the Amnicon River and features four different waterfalls. We intended to simply hike at this park, but ended up camping for two days because we loved it so much. There are only about 2 miles of trails within the park, but there is so much room to explore!
Pattison State Park
Pattison State Park is located just south of Superior, Wisconsin. It is home to Wisconsin's highest waterfall: Big Manitou Falls. The waterfall is 165 feet and lands into the Black River. There is a second waterfall, Little Manitou Falls, that is also very picturesque. A storm was rolling in when we visited this waterfall so we made our visit quick. There are approximately 9 miles of hiking trails; hopefully we get to come back someday!