Port Sulphur is a census-designated place on the West Bank of the Mississippi River in Plaquemines Parish, Louisiana, United States. The population was 1,760 at the 2010 census.The name Port Sulphur derives from the Freeport Sulphur Company in the early 1930s, when it set up logistics, refining, storage and shipping operations to support its Frasch Process sulphur mine at Lake Grande Ecaille, located 10 miles west of the town in the nearby marsh. The Grande Ecaille mine was the largest sulphur deposit in the world when it began operation in 1933, and remained in production until 1978.