Union County is a county in the U.S. state of Florida, the smallest in the state. As of the 2010 census, the population was 15,535. The county seat is Lake Butler. With a personal per capita income of $20,396 (as of 2017), it is the fourth-poorest county in the United States.
According to the U.S. Census Bureau, the county has an area of 250 square miles (650 km), of which 244 square miles (630 km) is land and 6.2 square miles (16 km) (2.5%) is water. It is the smallest county by area in Florida.
At the 2000 census, there were 13,442 people, 3,367 households and 2,606 families residing in the county. The population density was 56 per square mile (22/km²). There were 3,736 housing units at an average density of 16 per square mile (6/km²). The racial makeup of the county was 73.62% White, 22.84% Black or African American, 0.66% Native American, 0.31% Asian, 0.02% Pacific Islander, 1.04% from other races, and 1.50% from two or more races. 3.55% of the population were Hispanic or Latino of any race.
Of the 3,367 households, 41.80% had children under the age of 18 living with them, 57.70% were married couples living together, 15.00% had a female householder with no husband present, and 22.60% were non-families. 19.50% of all households were made up of individuals and 7.10% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.13.
The age distribution was 21.80% under the age of 18, 8.70% from 18 to 24, 39.80% from 25 to 44, 22.20% from 45 to 64, and 7.50% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 183.00 males. For every 100 females age 18 and over, there were 215.20 males. This extremely skewed gender distribution is the result of the county’s male prison population.
The median household income was $34,563, and the median family income was $37,516. Males had a median income of $28,571 versus $22,083 for females. The county’s per capita income was $12,333. About 10.50% of families and 14.00% of the population were below the poverty line, including 14.60% of those under age 18 and 16.20% of those age 65 or over.
The county suffers a death rate of about 1600 per 100,000 residents, the highest in the nation.