St. Marks is a city in Wakulla County, Florida, United States. It is part of the Tallahassee metropolitan area. The population was 293 at the 2010 census. As of 2018, the population estimated by the U.S. Census Bureau is 319. Geography St. Marks is located at . According to the United States Census Bureau, the city has a total area of , of which is land and 0.52% is water. Demographics St. Marks first appeared in the 1850 U.S. census with a total population of 189. 2020 census As of the 2020 United States census, there were 274 people, 167 households, and 140 families residing in the city. 2000 census As of the census of 2000, there were 272 people, 137 households, and 79 families residing in the city. The population density was . There were 168 housing units at an average density of . The racial makeup of the city was 93.75% White, 2.57% African American, 0.74% Native American, 0.37% Asian, 1.10% from other races, and 1.47% from two or more races. Hispanic or Latino of any race were 0.37% of the population. There were 137 households, out of which 16.1% had children under the age of 18 living with them, 43.1% were married couples living together, 9.5% had a female householder with no husband present, and 42.3% were non-families. 36.5% of all households were made up of individuals, and 8.8% had someone living alone who was 65 years of age or older. The average household size was 1.99 and the average family size was 2.56. In the city, the population was spread out, with 15.8% under the age of 18, 7.4% from 18 to 24, 27.6% from 25 to 44, 31.6% from 45 to 64, and 17.6% who were 65 years of age or older. The median age was 44 years. For every 100 females, there were 104.5 males. For every 100 females age 18 and over, there were 110.1 males. The median income for a household in the city was $25,156, and the median income for a family was $36,250. Males had a median income of $25,234 versus $21,458 for females. The per capita income for the city was $14,994. About 19.1% of families and 19.5% of the population were below the poverty line, including 27.3% of those under the age of eighteen and 6.7% of those 65 or over. On July 10, 2005, the storm surge