A nickname for the United States Department of State, whose offices were built in a formerly swampy area of Washington, D.C., known as Foggy Bottom because of vapors rising from the swamp.
The US Department of State:little affinity for the ''career boys'' of Foggy Bottom
[1950+; fr the name of a marshy region in Washington, DC, where the State Department and other federal buildings are located; also an allusion to the murkiness of some policies and pronouncements]