The Columbia Commonwealth was one of the thirteen commonwealths of the pre-War United States of America. Created in the early 21st century, it was comprised of the former states of Maryland and Virginia, as well as the District of Columbia, and borders the Southeast, East Central and Eastern Commonwealth.
The Capital Wasteland is the general name given to the ruins of Washington, D.C. and the region surrounding it (part of Maryland and Virginia), with what's left of the Potomac River dividing the wasteland roughly in two. Recent events have culminated in power struggles between both the Lyons' Brotherhood of Steel and the Outcasts, the Enclave, and the Super mutants. Raiders, Slavers, Mercenaries are rampant in the area.
The Maryland Wasteland is shown a small amount in the add-on Point Lookout. Swamplands and insane swampfolk abominations are excessive, and only a small group of tribals and wildlife reside there. Not much is known about the state, except that much of it wasn't hit by the bombs, and the damage done was the downfall of society, contact with the outside world, and the post-War radiation seeping into the state.
A small part of Maryland can be explored in Fallout 76. The entire area of The Mire that goes east of the Potomac River is a part of Maryland and the locations in it that can be explored are Braxson's Quality Medical Supplies, Crevasse Dam, Delano Grange, Haven Church, Ransacked bunker, Sam Blackwell's bunker, Southern Belle Motel, Scoot's Shack, Sunken Church, Tanagra Town, and Thunder Mountain Power Plant.
District of Columbia
- Little Lamplight (Fallout 3)
- Megaton (Fallout 3)
- Andale (Fallout 3)
- Bailey's Crossroads (Operation: Anchorage)
- Petersburg (Fallout 4)
- Baltimore (Fallout 3)
- Camp David (Fallout 4, mentioned)
- Damascus (Fallout 4)
- Hagerstown (Fallout 3)
- Paradise Falls (Fallout 3)
- Rockville (Fallout 3)
- Minefield (Fallout 3)
- Norfolk (mentioned in Point Lookout)
Parts of the Columbia Commonwealth, most notably around the Potomac river, appear in Fallout 3.