" " The assassination of President William McKinley in 1901 caused the Secret Service's mission to expand to include presidential protection. Photo12/UIG via Getty Images

When the Secret Service was started in 1865, counterfeiting was a major concern. Back then, an astounding one-third to one-half of the money flowing around the country was fake. Hence, President Abraham Lincoln's creation of the Secret Service to ferret out the criminals. Just two years later, in 1867, the agency's duties were expanded to include nabbing people trying to defraud the government via smuggling, mail robbery, land fraud and other means [sources: Blakemore, United States Secret Service].

Ironically, Lincoln was killed the evening he signed the legislation to create the Secret Service. But it wasn't until President William McKinley's assassination in 1901 — the third of a sitting president — that the Secret Service's duties were expanded to include presidential protection. Over the next century, the presidential protection piece was constantly tweaked, often as the result of another assassination or attempt.



Today, Secret Service protection is mandated for the president and vice president and their immediate families; former presidents, spouses and minor children under age 16; major presidential and vice presidential candidates and their spouses; and foreign heads of state and their spouses when they're visiting the U.S. (A president's adult children may decline protection.)

Secret Service protection is also mandated at events that are designated National Special Security Events by the head of the Department of Homeland Security — for instance, the Super Bowl. At these events the Secret Service will take the lead in security operations. It will collaborate with local law enforcement to ensure that everyone — both dignitaries and the general public — are kept safe [source: United States Secret Service.]

Over this same 100-plus years, other changes have occurred inside the agency. For example, the Secret Service assumed control of the White House Police Force in 1930 and the Treasury Guard Force, now called the Treasury Police Force, in 1937. In 1971, the agency swore in its first five female special agents. And in 2003, the Secret Service was transferred from the Treasury Department to the new Department of Homeland Security [source: United States Secret Service].

After the Sept. 11, 2001, terrorist attacks, and the subsequent passage of the USA Patriot Act, the agency was tasked with creating a national network of Electronic Crimes Task Forces (ECTFs) based on a model then being used in New York. The ECTFs work to prevent and combat attacks on America's citizens, institutions and critical structures, namely those involving cybercrime.

The ECTFs are composed of local, state and federal law enforcement personnel, plus prosecutors and members of private industry and academia. Everyone on the task forces works together to bring his or her special expertise to fight such crimes as bank fraud, viruses and worms, internet threats and identity theft. Today there are 39 ECTFs scattered across the nation and in Europe. In addition, the Secret Service collaborates with another 46 Financial Crimes Task Forces [sources: U.S. Department of Homeland Security, United States Secret Service].