Bayou St. John (French: Bayou Saint-Jean) is a bayou within the city of New Orleans, Louisiana.
The Bayou as a natural feature drained the swampy land of a good portion of what was to become New Orleans, into Lake Pontchartrain. In its natural state, it extended much farther than today; 18th- and early 19th-century maps show it had tributaries or branches (at least seasonally) reaching into what are now the Broadmoor neighborhood, the New Orleans Central Business District just back from St. Charles Avenue above Lee Circle, the Carrollton neighborhood, the Treme neighborhood, and a branch connecting to Bayou Gentilly.
