Head of Passes is where the main stem of the Mississippi River branches off into three distinct directions at its mouth in the Gulf of Mexico: Southwest Pass (west), Pass A Loutre (east) and South Pass (centre). They are part of the "Bird's Foot Delta", the youngest lobe of the evolving

Mississippi River Delta The Mississippi River Delta is the confluence of the Mississippi River with the Gulf of Mexico in Louisiana, southeastern United States. The river delta is a area of land that stretches from Vermilion Bay on the west, to the Chandeleur Isla ...

. The ''Head of Passes'' is considered to be the location of the mouth of the Mississippi River. The US Army Corps of Engineers maintains a 45-foot (13.7 m) shipping channel from the mouth of Southwest Pass—20 miles (32 km) downriver from the Head—up to

Baton Rouge Baton Rouge ( ; ) is a city in and the capital of the U.S. state of Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-sma ...

, the US's farthest inland deep-water port. The Mouth of Passes is the aggregate of the individual mouths of the passes connected to the Head of Passes, including the Southwest, South, North Passes and Pass a Loutre. While the majority of the discharge of the Mississippi River flows through these mouths, a portion of the river flows out of the Atchafalaya River mouth, and a small portion continues to seep out of the 200 miles (300 km) of the Delta shoreline. During the American Civil War, Head of Passes was the site of several naval battles. The Anaconda Plan called for a large Union blockade of the Confederacy, and included plans to control the Mississippi River. This began in 1861 with a Union blockade stationed at the Head of Passes. This occupation resulted in the Battle of the Head of Passes, where the blockading forces were temporarily driven from the area. Ships involved in the ensuing conflict at the location include the , the , and the .

Port Eads Port Eads is a populated place at the southern tip of the Mississippi River, also known as South Pass, in Plaquemines Parish, Louisiana, United States. The Mississippi River in the 100-mile-plus stretch between the Port of New Orleans and the Gulf ...

is located at the southern tip of South Pass.

AHP datum

The Head of Passes is the datum from which mileages on the Lower Mississippi River are measured.

Algiers Point Algiers Point is a location on the Lower Mississippi River in New Orleans, Louisiana. In river pilotage, Algiers Point is one of the many points of land around which the river flows—albeit a significant one. Since the 1970s, the name Algie ...

, for instance, is at mile 94.6 AHP (above Head of Passes). Cairo, Illinois, is at mile 953.8 AHP. Mileages downstream from Head of Passes are labelled BHP (below Head of Passes).{{cite book , first = Marion , last = Bragg , year = 1977 , url = http://www.mvn.usace.army.mil/pao/History/MRnames/MRnamesTOC.htm , title = Historic Names and Places on the Mississippi River , publisher = Mississippi River Commission , location = Vicksburg , url-status = dead , archiveurl = https://web.archive.org/web/20060128110648/http://www.mvn.usace.army.mil/pao/history/MRnames/MRnamesTOC.htm , archivedate = 2006-01-28

Notes

Mississippi River Landforms of Plaquemines Parish, Louisiana