A fan map for fallout depicting Chicago, now known as the Dreg Heap. Though not hit with nuclear missiles by the Great War, infiltrators and 5th columnists in the city set off a nuclear bomb beneath the Chicago Loop soon after the Bombs began falling.

The city remains a hotbed of factional disputes; between Enclave Remnants who control the USS Cradley and several covert bunkers and other facilities throughout the city; the Brotherhood of Steel which controls Midway Airport and the bombed out ruins of O’Hare as well as other settlements and checkpoints around the city; to the Faithful of Thoria (like the Children of Atom) who created their own sacred sanctuary in glow of the Crater; to various raider and settler groups.

Other major groups include Chinatown, which was turned into a walled ghetto in the years leading up to the Great War. As a result, however, the neighborhood was quite defensible once the US soldiers fled. The town of Stickney still maintains a water treatment plant that provides water for much of the settlers of the area as well.

Due to the city’s geography, as well as climate change from the Great War, much of the city is flooded with swampy, polluted water. Boats are necessary for much of the area, and the city is known for its large populations of Bloodbugs, Bloatflies, and Radroaches, as well as Mirelurk.

However, the city is also home to Dregs, amorphous masses of rotting plastic, meat, trash and petroleum created before the war by WestTek as a means to deal with petroleum pollution products, perhaps as a means to reclaim it for use. After the war, however, the normally harmless microbes became voracious colonies that slowly ooze around consuming anything organic in their path.

When the weather turns just right, huge volumes of trash roll in from the Lake onto Chicago’s shores, causing booms of Dreg growth. Settlers have taken to lighting pyres on the docks and beaches to keep them at bay during these times, as they hate intense heat.