According to the U.S. Census Bureau, the county has a total area of, of which is land and is water. The majority of Long County, roughly centered on Ludowici, is located in the Altamaha River sub-basin of the basin by the same name. The county's northeastern portion, east of Glennville and northwest of Walthourville, is located in the Canoochee River sub-basin of the Ogeechee River basin. Long County's southeastern portion is located in the Ogeechee Coastal sub-basin of the larger Ogeechee basin.
As of the census of 2000, there were 10,304 people, 3,574 households, and 2,676 families living in the county. The population density was 26 people per square mile. There were 4,232 housing units at an average density of 11 per square mile. The racial makeup of the county was 68.41% White, 24.25% Black or African American, 0.73% Native American, 0.57% Asian, 0.25% Pacific Islander, 3.91% from other races, and 1.87% from two or more races. 8.44% of the population were Hispanic or Latino of any race. There were 3,574 households out of which 45.60% had children under the age of 18 living with them, 55.00% were married couplesliving together, 14.50% had a female householder with no husband present, and 25.10% were non-families. 19.60% of all households were made up of individuals and 5.20% had someone living alone who was 65 years of age or older. The average household size was 2.88 and the average family size was 3.28. In the county, the population was spread out with 33.10% under the age of 18, 14.20% from 18 to 24, 31.00% from 25 to 44, 15.90% from 45 to 64, and 5.80% who were 65 years of age or older. The median age was 26 years. For every 100 females, there were 102.10 males. For every 100 females age 18 and over, there were 100.70 males. The median income for a household in the county was $30,640, and the median income for a family was $32,473. Males had a median income of $26,416 versus $18,732 for females. The per capita income for the county was $12,586. About 17.60% of families and 19.50% of the population were below the poverty line, including 26.00% of those under age 18 and 19.80% of those age 65 or over.
2010 census
As of the 2010 United States Census, there were 14,464 people, 5,023 households, and 3,654 families living in the county. The population density was. There were 6,039 housing units at an average density of. The racial makeup of the county was 62.4% white, 25.2% black or African American, 0.8% Asian, 0.6% American Indian, 0.4% Pacific islander, 7.2% from other races, and 3.4% from two or more races. Those of Hispanic or Latino origin made up 12.3% of the population. In terms of ancestry, 12.1% were German, 10.6% were Irish, 8.3% were American, and 7.1% were English. Of the 5,023 households, 44.2% had children under the age of 18 living with them, 48.8% were married couples living together, 18.1% had a female householder with no husband present, 27.3% were non-families, and 22.4% of all households were made up of individuals. The average household size was 2.81 and the average family size was 3.28. The median age was 30.6 years. The median income for a household in the county was $41,186 and the median income for a family was $46,654. Males had a median income of $30,921 versus $25,675 for females. The per capita income for the county was $15,068. About 11.6% of families and 15.8% of the population were below the poverty line, including 20.6% of those under age 18 and 20.0% of those age 65 or over.
One of the most anti-Catholic counties in the United States, it was an ancestrally Democratic country that heavily voted against Catholic Democratic candidates. It has become a safe Republican county since 2000.
