Wisconsin Constitution Article II § 1 – State boundary
It is hereby ordained and declared that the state of Wisconsin doth consent and accept of the boundaries prescribed in the act of congress entitled “An act to enable the people of Wisconsin territory to form a constitution and state government, and for the admission of such state into the Union,” approved August sixth, one thousand eight hundred and forty-six, to wit: Beginning at the northeast corner of the state of Illinois – that is to say, at a point in the center of Lake Michigan where the line of forty-two degrees and thirty minutes of north latitude crosses the same; thence running with the boundary line of the state of Michigan, through Lake Michigan, Green Bay, to the mouth of the Menominee river; thence up the channel of the said river to the Brule river; thence up said last-mentioned river to Lake Brule; thence along the southern shore of Lake Brule in a direct line to the center of the channel between Middle and South Islands, in the Lake of the Desert; thence in a direct line to the head waters of the Montreal river, as marked upon the survey made by Captain Cramm; thence down the main channel of the Montreal river to the middle of Lake Superior; thence through the center of Lake Superior to the mouth of the St. Louis river; thence up the main channel of said river to the first rapids in the same, above the Indian village, according to Nicollet’s map; thence due south to the main branch of the river St. Croix; thence down the main channel of said river to the Mississippi; thence down the center of the main channel of that river to the northwest corner of the state of Illinois; thence due east with the northern boundary of the state of Illinois to the place of beginning, as established by “An act to enable the people of the Illinois territory to form a constitution and state government, and for the admission of such state into the Union on an equal footing with the original states,” approved April 18th, 1818.