The 4,600 members of the Secret Service are divided between the special agents division and the uniformed division. The plain-clothes special agents protect the President, First Family, Vice-President and family. They also protect visiting heads of state and government.

The uniformed agents patrol the grounds and corridors of the White House and check all visitors. The Secret Service also has overseas liaison offices in Paris, London, Bonn, Rome and Bangkok. The Secret Service was set up by President Abraham Lincoln in 1865 as part of the Treasury to prevent counterfeiting of money. He was assassinated the same evening.

Protection of presidents was added to the agents' duties in 1901 only after two further assassinations.