Bayou St. John was formed thousands of years ago by a series of floods that carved out a channel between Lake Pontchartrain and the Mississippi River. The bayou was originally much wider and deeper than it is today, but over time it has been filled in by sediment and debris.
In the early 1800s, Bayou St. John was an important transportation route for steamboats and other vessels. The bayou was also used as a source of fresh water for the city of New Orleans. In the late 1800s, the Inner Harbor Navigation Canal was constructed, which diverted much of the traffic from Bayou St. John.
Today, Bayou St. John is a popular recreational destination for residents of New Orleans and tourists alike. The bayou is lined with parks and marinas, and is also home to a number of restaurants and shops. Bayou St. John is also a popular spot for fishing and boating, and is home to a variety of wildlife, including alligators, turtles, and birds.