The first, real incarnation of APEC was called "The Stereoscopic Exchange Club" and was organized in England in 1859. It included about 50 members and remained active until at least 1865. This club was probably part of the inspiration for the 1st American club, however, they were not officially related.
Henry T. Anthony, with two friends, F. F. Thompson and Charles Wagner Hull, organized the Amateur Photographic Exchange Club in November 1861. F. F. Thomspon served as club secretary. The club functioned until September 1863, soon after the Civil War battle of Gettysburg, because both Anthony and Hull were drafted into the Union forces.
17 people were originally invited to join, and 32 eventually were associated with APEC I in one way or another. Membership was purposefully kept small because each member was required to send every other member at least one stereoscopic photographic print six times a year at prescribed intervals.