Gretna is located in Jefferson county Louisiana with a geographic area of 4.0 square miles. The total population in Gretna is 17,746 with 50.4% male and 49.6% female. Children under age 5 represent 4.9% of the population, under age 18 equal 17.2% of the population and over age 65 is 20.0% of the population. The median household income is $41,409, per capita income is $28,584. There are a total of 7,891 housing units with 53.1% owner occupied. Education includes 20.7% of residents that are high school graduates and 23.1% with a bachelor's degree or higher. The average temperature in Gretna in the summer is 81 degrees, and in the winter 51 degrees.