Lauderdale County was established in 1818, a year before Alabama became a state, Florence, the county seat of Lauderdale County, was also established in 1818. At this time a group of investors, under the name of Cypress Land Company purchased from the government 5,515 acres (22.32 km) of land comprising of the original town site. Other towns in Lauderdale County competing for early settlers because of their proximity to the river were Savage's Spring, nine miles (14 km) below Florence and Waterloo, some 20 miles (32 km) downriver.
Among the older settlements in the county is Center Star, located between Killen and Rogersville. This area was once claimed by both the Chickasaw's and Cherokees, necessitating a cession of territory from each tribe before the settlement could be established. The remains of an old Indian village could be seen at one time southwest of Center Star. Other old settlements included Middleton and Elgin, the latter known first as Ingram's Elgin Cross Roads.
Rogersville, lying some 23 miles (37 km) to the east of Florence, was named for John Rogers, an Indian Trader, whose sons were fast friends of the great Sam Houston. The late Will Rogers is said to have been a descendant of this same family. An early ferry that operated for many years was Lamb's Ferry near Rogersville.
Lexington, Springfield, and Anderson lie to the north of the Lee Highway, the town of Lexington being a part of the territory once claimed by the Cherokees. Many of the settlers of that area came from Tennessee and the Carolinas. The first post office of record at Lexington was on the Loretto Road, north of town, in 1880. Mail at that time was brought in from Loretto, Tennessee, by horseback and carts.
The town of St. Florian was established in 1872 on the Jackson Highway and named by its German Catholic founders for their patron saint.
As of the census of 2000, there were 87,966 people, 36,088 households, and 25,153 families residing in the county. The population density was 131 people per square mile (51/km²). There were 40,424 housing units at an average density of 60 per square mile (23/km²). The racial makeup of the county was 88.38% White, 9.85% Black or African American, 0.25% Native American, 0.35% Asian, 0.02% Pacific Islander, 0.36% from other races, and 0.79% from two or more races. 1.02% of the population were Hispanic or Latino of any race.
In 2005 87.8% of the county population was non-Hispanic whites. African Americans were 9.7% of the population and Latinos 1.2% of the population.
In 2000 there were 36,088 households out of which 30.40% had children under the age of 18 living with them, 55.80% were married couples living together, 10.80% had a female householder with no husband present, and 30.30% were non-families. 26.40% of all households were made up of individuals and 11.00% had someone living alone who was 65 years of age or older. The average household size was 2.39 and the average family size was 2.89.
In the county the population was spread out with 23.00% under the age of 18, 10.10% from 18 to 24, 27.90% from 25 to 44, 23.90% from 45 to 64, and 15.10% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 91.70 males. For every 100 females age 18 and over, there were 88.20 males.
The median income for a household in the county was $33,354, and the median income for a family was $41,438. Males had a median income of $33,943 versus $20,804 for females. The per capita income for the county was $18,626. About 10.50% of families and 14.40% of the population were below the poverty line, including 18.50% of those under age 18 and 11.30% of those age 65 or over.