Currently has a population of about 10,000 located on the gulf coastal plain of southwestern Arkansas in the U.S. The town was established in the 1840's by a blacksmith just west of the Ouachita River near a salt mining operation and was known as "Blakely Town" until the 1880's. The name change was an homeage to the city of Philadelphia and meant to convey the meaning of "the Ark of brotherly love".
Arkadelphia is home to two small colleges, one Henerson State University is a state - sponsered institution, while Ouachita Baptist University is a Southern Baptist institution. Timber and row-cropping are the main industries in the area along with a few light manufacturing industries.
A town in Alabama has the same name, but I don't know anthing about it.