Louisiana v. Mississippi
Headline: Mississippi–Louisiana river border clarified as Court confirms pre-1912 river channel as the legal boundary, awarding gradually added land to Louisiana and keeping boundary despite a sudden 1912–13 river jump.
Holding: The Court held that the state line is the river’s main navigable channel as it existed immediately before the 1912–13 sudden shift, and that land gained gradually by accretion belonged to Louisiana.
- Treats land gained by gradual accretion as belonging to the adjacent state (Louisiana).
- Holds sudden river jumps (avulsions) do not shift the state boundary.
- Orders a survey to fix the pre-1912 river channel as the legal boundary.
Summary
Background
The dispute involved land beside the Mississippi River where the river’s channel shifted over many decades. Louisiana said slow buildup of land (accretion) along its shore moved the state line eastward and gave it new territory. Mississippi argued the changes were not all gradual and that it had exercised control over the area. Surveys from 1823–24, 1882, 1894, and 1912–13 and testimony about local use and maps formed the factual record.
Reasoning
The central question was whether the boundary moved when the river slowly changed course or when it suddenly jumped in 1912–13. The Court accepted the special master’s factual findings. It concluded that from 1823 to 1912 the river’s eastward shift happened largely by gradual erosion and accretion, which makes newly attached land belong to Louisiana. The 1912–13 change was a sudden avulsion (a quick river jump), which does not move the legal state line, so the boundary remains at the thread of the navigable channel as it existed immediately before that sudden change. The Court also found Mississippi failed to show long-standing possession or sovereign control over the disputed land.
Real world impact
The Court ordered a commission to locate the river’s main channel as it was just before the 1912–13 avulsion and declared that line the legal border in the disputed stretch. Practically, land added gradually to Louisiana’s shore is awarded to Louisiana, sudden changes in the river do not shift state lines, and Mississippi’s claims of possession were rejected. The decision resolves title and directs a survey to mark the boundary on the ground.
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