Virginia Foscue's Place Names in Alabama notes that a post office was established in Arkadelphia in 1854. She also discusses the origin of the name. "One proposed explanation is that the name was that of the wife of John A. Donaldson, the first postmaster. However, it may be a combination of Ark, the name of an early nearby settlement and PO in Winston Co., and -adelphia, a pseudo-Greek combination meaning 'brother-place,' probably taken from Philadelphia."
There is a much larger Arkadelphia, the seat of Clark County, in Arkansas. According to the U.S. Geological Survey's Geographic Names Information System, only two towns in the U.S. have that name. Also according to the GNIS, the Alabama town once had an elementary school, and Cullman County also has an Arkadelphia Mine and Arkadelphia Mountain.
Because of shifting boundaries, Arkadelphia has been located in three Alabama counties: Walker beginning in 1820, Blount in 1850 and finally Cullman in 1901. The community was a stagecoach stop on the Huntsville to Tuscaloosa road and once included a tavern and blacksmith shop. The post office closed in December 1968.
Arkadelphia's first school was built before 1900, and several different buildings housed the facility over the years. In 1962 the school was consolidated with one in Hanceville. In 1921-22 the town had a four-teacher school with 117 students in grades 1-7 and 20 in grades 8-12. By 1959 that elementary school had 59 students and three teachers.
Arkadelphia is not listed in the 2000 or 2010 U.S. Census cities and towns in Alabama. The Wikipedia article linked above gives an 1880 U.S. Census population of 195. In 1950 the Cullman County voting precinct 7, Arkadelphia, had 944 people, according to the Alabama Almanac and Book of Facts 1955-1956.
Unless otherwise noted, much of this information came from Margaret Jean Jones' 1972 book, Combing Cullman County. On page 106 she has a photograph of a house built by Jeff Calloway in Arkadelphia in 1820. She also describes a 12-room house built in 1884 by Dr. Charles Drennen that included a clinic and hospital. Those facilities closed soon after 1900 and the house eventually became an apartment building. At the time Jones wrote, the house was still standing in Arkadelphia.
Various comments are below the photos. All photos are mine unless otherwise noted.
Many times I've passed this exit on I-20/59 in Birmingham and wondered where or what is Arkadelphia?
Source: AA Roads
There is another United Methodist Church on Arkadelphia Road near Birmingham Southern College. This church also serves the community of Bremen. Both churches are in the North Alabama Conference of the United Methodist Church.
A Methodist church was first organized in the community in 1867.
Here's a view of Highway 91 toward the Arkadelphia cemetery.
I think Swann's operated until fairly recently; the store below is a reminder of much older days in the community.
In her book Jones notes, "The local trade area now has only two general stores..." Even that has changed since she wrote it in 1972.
The community center applied to the state as a non-profit entity in September 1991.
For some strange reason, although I stopped right in front of it, I did not photograph the church itself!
The cemetery is large, well maintained and still active. According to an inventory available here, graves date to the early 1800's.
This 1902 "Official Map of Cullman County, Alabama" shows Arkadelphia in the extreme southern portion of the county. The community remains on official state highway maps, such as these recent ones below.