St. Mary Parish (French: Paroisse de Sainte-Marie) is a parish located in the U.S. state of Louisiana. As of the 2010 census, the population was 54,650. The parish seat is Franklin. The parish was created in 1811.
According to the U.S. Census Bureau, the parish has a total area of 1,119 square miles (2,900 km), of which 555 square miles (1,440 km) is land and 564 square miles (1,460 km) (50%) is water. Cypremort Point State Park is located in the parish on Vermilion Bay.
As of the census of 2000, there were 53,500 people, 19,317 households, and 14,082 families residing in the parish. The population density was 87 people per square mile (34/km²). There were 21,650 housing units at an average density of 35 per square mile (14/km²). The racial makeup of the parish was 62.79% White, 31.79% Black or African American, 1.39% Native American, 1.64% Asian, 0.02% Pacific Islander, 0.88% from other races, and 1.50% from two or more races. 2.15% of the population were Hispanic or Latino of any race. 5.43% reported speaking French or Cajun French at home, while 2.45% speak Spanish and 1.59% Vietnamese.
There were 19,317 households out of which 36.70% had children under the age of 18 living with them, 51.00% were married couples living together, 16.50% had a female householder with no husband present, and 27.10% were non-families. 23.20% of all households were made up of individuals and 8.70% had someone living alone who was 65 years of age or older. The average household size was 2.74 and the average family size was 3.23.
In the parish the population was spread out with 29.70% under the age of 18, 8.70% from 18 to 24, 28.70% from 25 to 44, 21.90% from 45 to 64, and 11.00% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 95.00 males. For every 100 females age 18 and over, there were 92.20 males.
The median income for a household in the parish was $28,072, and the median income for a family was $33,064. Males had a median income of $31,570 versus $18,341 for females. The per capita income for the parish was $13,399. About 20.60% of families and 23.60% of the population were below the poverty line, including 31.30% of those under age 18 and 19.00% of those age 65 or over.