|The following is based on Fallout Tactics and some details might contradict canon.|
The rubble-strewn city of Jefferson is what remains of Jefferson City, Missouri. One of Gammorin's super mutant staging areas was located there. The mutants had a semi-permanent military base in the ruins of Jefferson.
Around 2197, after General Simon Barnaky was taken prisoner by Toccomatta, the Brotherhood of Steel sent a squad to Jefferson believing the structure to be a weapons manufacturing plant. The Warrior's objective was to render all of the power generators permanently inoperative. During the last minutes of siege, the female super mutant commander was killed.
As it turned out, the super mutants were not manufacturing weapons, but were working on a cure to the super mutant sterility. Erkal, the mutant scientist runs a lab full of mutant freaks - his guinea pigs - and other test subjects in glass containers. This laboratory was either destroyed or taken over by the Brotherhood (depending on the player's actions during the mission).
The mission in Jefferson consists of finding and destroying all of the generators powering a factory controlled by the super mutants.
Jefferson appears only in Fallout Tactics.