Aftermath has its beginnings in several different groups and traditions. Wednesday nights were the nights that smokes and karma went Swing dancing. WWA had a loose tradition of a Friday Afternoon Club that met at the the Billy Goat II Tavern, going back to 1996. NSG decompressed at a wide range of taverns and locales (including the infamous Oasis in Rogers Park).
As the last remnants of the old Republic were swept away, these friends solidified the Wednesday evening tradition, first at at Cactus (an over-priced trader bar) and then at the locations they now frequent. A brief flirtation with visiting various beer gardens around the Chicago area died a swift and painless death earlier in the summer of '99.
Friendship and inertia seem to be the primary forces guiding the group.