Union County, Florida  Union County is a county located in the north central portion of 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. Union County was created in 1921 from part of Bradford County. It was named to honor the concept of unity. Union County is the location of Union Correctional Institution and the Reception and Medical Center (RMC). Union CI is a maximum security prison and is home to part of Florida's Death Row. The death chamber is located at nearby Florida State Prison (FSP) in Bradford County. Florida State Prison also houses some death-row inmates. According to the U.S. Census Bureau, the county has an area of , of which is land and (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.