As of 2019, the median household income in Gretna was $47,244. Males had a median income of $44,902 versus $31,992 for females. Approximately 17.8% of the population lived at or below the poverty line. In 2010, the median income for a household in the city was $28,065, and the median income for a family was $31,881. Males had a median income of $28,259 versus $21,019 for females. The per capita income for the city was $15,735. About 20.8% of families and 24.2% of the population were below the poverty line, including 34.7% of those under age 18 and 20.2% of those age 65 or over.
