According to the United States Census Bureau, the city has a total area of 3.6 square miles (9.2 km²): 3.2 square miles (8.3 km²) of it is land, and 0.4 square miles (1.0 km²) of it (10.64%) is water.
There were 4,211 households out of which 32.7% had children under the age of 18 living with them, 41.1% were married couples living together, 20.8% had a female householder with no husband present, and 32.3% were non-families. 26.7% of all households were made up of individuals and 10.5% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.10.
In the city the population was spread out with 27.5% under the age of 18, 8.9% from 18 to 24, 29.9% from 25 to 44, 21.2% from 45 to 64, and 12.5% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 90.5 males. For every 100 females age 18 and over, there were 84.6 males.
The median income for a household in the city was $27,218, and the median income for a family was $31,187. Males had a median income of $29,398 versus $18,916 for females. The per capita income for the city was $13,160. About 17.9% of families and 22.4% of the population were below the poverty line, including 33.7% of those under age 18 and 9.5% of those age 65 or over.
The following schools in Westwego serve city residents:
Most city residents are zoned to Worley Middle School (Westwego) and Higgins High School (Unincorporated Jefferson Parish). Some are zoned to Marrerro Middle School (Unincorporated Jefferson Parish) and John Ehret High School (Unincorporated Jefferson Parish).