Louisiana v. Mississippi

Background

The State of Louisiana sued and asked the court to fix the true boundary with Mississippi in the waters around Lake Borgne and Mississippi Sound. The case was heard on the written pleadings and proofs and was argued by lawyers. The Court considered maps made from parts of U.S. Coast and Geodetic Survey charts Nos. 190 and 191 when describing the area at issue.

Reasoning

The central question was where the boundary between the two states runs through Lake Borgne and Mississippi Sound. The Court found that Louisiana was entitled to a decree recognizing a specific line. It identified the boundary as the deep-water sailing channel that emerges from the most eastern mouth of the Pearl River into Lake Borgne, runs through the northeast corner of Lake Borgne north of Half Moon (Grand Island), then east and south through Mississippi Sound and South Pass between Cat Island and Isle à Pitre to the Gulf of Mexico, as shown on the cited map. The Court ordered that Mississippi be enjoined from disputing Louisiana’s sovereignty and ownership of the territory south and west of that line.

Real world impact

The ruling fixes which state has sovereignty and ownership over the specified land and waters, and it prevents Mississippi’s officers, agents, and citizens from contesting Louisiana’s control there. The Court also ordered that Mississippi bear the costs of the suit. This is a final decree from the Court defining the boundary and assigning enforcement and expense consequences to Mississippi.