Geography and climate
St. Augustine is located at 29°53′39″N, 81°18′48″W (29.894264, -81.313208).
According to the United States Census Bureau, the city has a total area of 27.8 km² (10.7 mi²). 21.7 km² (8.4 mi²) of it is land and 6.1 km² (2.4 mi²) of it (21.99%) is water.
Access to the Atlantic Ocean is via the St. Augustine Inlet of the Matanzas River.
As of the census of 2000, there were 11,592 people, 4,963 households, and 2,600 families residing in the city. The population density was 534.7/km² (1,384.6/mi²). There were 5,642 housing units at an average density of 260.3/km² (673.9/mi²). The racial makeup of the city was 81.21% White, 15.07% African American, 0.41% Native American, 0.72% Asian, 0.09% Pacific Islander, 0.88% from other races, and 1.61% from two or more races. Hispanic or Latino of any race were 3.11% of the population.
There were 4,963 households out of which 18.6% had children under the age of 18 living with them, 37.4% were married couples living together, 12.4% had a female householder with no husband present, and 47.6% were non-families. 36.7% of all households were made up of individuals and 14.5% had someone living alone who was 65 years of age or older. The average household size was 2.11 and the average family size was 2.76.
In the city the population was spread out with 16.1% under the age of 18, 15.3% from 18 to 24, 23.9% from 25 to 44, 25.2% from 45 to 64, and 19.5% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 84.6 males. For every 100 females age 18 and over, there were 81.4 males.
The median income for a household in the city was $32,358, and the median income for a family was $41,892. Males had a median income of $27,099 versus $25,121 for females. The per capita income for the city was $21,225. About 9.8% of families and 15.8% of the population were below the poverty line, including 25.8% of those under age 18 and 10.0% of those age 65 or over.