United States government

According to United States Constitution the President may require the Opinion of the principal Officer in each of the executive Departments, upon any subject relating to the Duties of their respective Offices (Article Two, Section 2, Clause 1).

Before the War
Government branches mentioned Fallout games: Possible Cabinet positions:
 * War Department - mentioned in Maxson Log (Department of Defence - according to van Buren screenshot concerning HERMES armor and according to Fallout 3 "Faction Profile – the Brotherhood of Steel"),
 * department responsible for war bonds.
 * Environmental Protection Agency.
 * Secretary of War,
 * Secretary of Treasure,
 * Administrator of the Environmental Protection Agency (cabinet level administration officer).

The Enclave
The Cabinet was addresse of the Project report from United States Chemical Corps and Power Plant Operations report from Atomic Energy Commision.
 * The only known cabinet level administration officer in the Enclave was Vice-President (President of the Senate also), the first person in the presidential line of succession.
 * Secret Service was present there also - because of Divergence in Fallout world it could be overseen by Department of Treasure.

Very likely Cabinet present in the Enclave was minimally staffed (eg. the first American President appointed a Cabinet of four people).

See also: USA, Enclave.