Wisconsin v. Michigan
Supreme Court of the United States
Argued March 2, 1936 Decided March 16, 1936
Full case name	The State of Wisconsin v. The State of Michigan
Citations	297 U.S. 547 (more) 56 S. Ct. 584; 80 L. Ed. 856
Case history
Prior	295 U.S. 455 (1935).
Holding
The boundary between Michigan and Wisconsin is amended as stated
Court membership
Chief Justice Charles E. Hughes Associate Justices Willis Van Devanter · James C. McReynolds Louis Brandeis · George Sutherland Pierce Butler · Harlan F. Stone Owen Roberts · Benjamin N. Cardozo
Case opinion
Majority	Unanimous

Disputed area

Disputed area Ships passing between Green Bay (left) and Lake Michigan (right) traveled between various islands. Show map of Wisconsin Disputed area Disputed area (the United States) Show map of the United States
Geography
Coordinates	45°19′17″N 86°54′58″W / 45.321487°N 86.916073°W / 45.321487; -86.916073
Major islands	4: Detroit, Plum, Rock & Washington

Two Supreme Court cases, Wisconsin v. Michigan, 295 U.S. 455 (1935) and Wisconsin v. Michigan, 297 U.S. 547 (1936), settled a territorial dispute between Wisconsin and Michigan.

Background

The 1836 boundary description between Wisconsin and Michigan described the line through northwest Lake Michigan as "the most usual ship channel". This description needed clarification as two routes were in use into Green Bay. Multiple islands lay in between and all were claimed as part of both Door County, Wisconsin, and Delta County, Michigan. A similar case, Michigan v. Wisconsin 270 U.S. 295 (1926), had previously been brought to the Supreme Court but was dismissed.

Decision

In 1936, the Supreme Court decision chose the ship channel through the Rock Island Passage as the more common, so Wisconsin retained the intervening water area with its islands: Plum, Detroit, Washington, Hog, and Rock.