Louisiana v. Mississippi
Headline: Settles Mississippi–Louisiana river boundary after 1912–1913 avulsion, upholds Special Master’s report, and orders a federal survey to mark the middle navigable channel as the state line.
Holding: The Court upheld the Special Master’s findings and decreed that the boundary is the middle of the Mississippi River’s navigable channel as it lay when the old channel ceased flowing after the 1912–1913 avulsion.
- Declares the state line is the middle of the navigable channel as it lay after the avulsion.
- Creates a federal-ordered survey to locate and place permanent boundary markers.
- Changes local jurisdiction and property control once the court approves the survey.
Summary
Background
The State of Louisiana sued the State of Mississippi over where their boundary lies along a stretch of the Mississippi River after an avulsion (a sudden river course change) in 1912–1913. A Special Master, Thomas G. Haight, prepared a report with findings, and Mississippi filed exceptions to that report. On February 2, 1931, the Court reviewed the Special Master’s record, evidence, and briefs and sustained Louisiana’s bill of complaint and the Special Master’s recommendations.
Reasoning
The key question was how to determine the legal boundary after the river changed course by avulsion. The Court agreed with the Special Master that the relevant boundary is the middle of the river’s navigable channel as it existed at the time the old channel stopped carrying the main current because of the avulsion. The Court overruled Mississippi’s objections, approved the Special Master’s findings, and appointed Samuel S. Gannett as commissioner to run, plat, and mark the line using the best available scientific methods and to file a full report and maps for the Court to confirm.
Real world impact
Once the appointed commissioner completes the survey and the Court confirms it, the newly marked line will be the official state boundary in the affected area. That process will determine which state controls particular riverbanks and land, and it requires permanent boundary markers, field notes, and an opportunity for objections within forty days after the report is filed. The decree also addresses commissioner duties, compensation, and procedures if a vacancy occurs.
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