See W. H. Smith, ed., The St. Clair Papers (2 vol., 1882, repr. 1971); biography by F. E. Wilson (1944).
As of 2000 the population was 64,742. It has one county seat in Ashville and another in Pell City. While other counties in Alabama have multiple courthouses, St. Clair County is the only county in Alabama with more than one county seat.
There were 24,143 households out of which 35.10% had children under the age of 18 living with them, 62.80% were married couples living together, 10.00% had a female householder with no husband present, and 23.60% were non-families. 20.80% of all households were made up of individuals and 8.20% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.01.
In the county the population was spread out with 25.40% under the age of 18, 7.90% from 18 to 24, 30.70% from 25 to 44, 24.30% from 45 to 64, and 11.70% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 101.80 males. For every 100 females age 18 and over, there were 98.80 males.
The median income for a household in the county was $37,285, and the median income for a family was $43,152. Males had a median income of $33,914 versus $24,433 for females. The per capita income for the county was $17,960. About 9.60% of families and 12.10% of the population were below the poverty line, including 15.20% of those under age 18 and 12.60% of those age 65 or over.