Head of Passes is where the main stem of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

branches off into three distinct directions at its mouth in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

: 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 , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

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 The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...

, Head of Passes was the site of several naval battles. The Anaconda Plan called for a large

Union blockade The Union blockade in the American Civil War was a naval strategy by the United States to prevent the Confederacy from trading. The blockade was proclaimed by President Abraham Lincoln in April 1861, and required the monitoring of of Atlantic ...

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 Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metro ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

, 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