A History of Private Investigations in the U.S.

The history of private investigators in the United States originates with Allan Pinkerton. The term, “private eyes,” got it’s start, with his company slogan, “we never sleep.” Pinkerton’s agents were famous for tracking western outlaws Jesse James, the Reno brothers, and Butch Cassidy and the  Sundance Kid.
Allan Pinkerton originally immigrated to this country in 1843. By 1850, he had founded the Chicago-based Pinkerton National Detective Agency, which would quickly become the industry’s largest private security companies. Pinkerton became famous when he foiled a plot to assassinate then President-Elect Abraham Lincoln.
In addition to tracking down and apprehending criminals, the early private security industry performed many other duties now associated with federal and state law enforcement: guarding interstate railroad and stagecoach shipments, investigating crimes and providing security advice to banks and other businesses that were frequent targets of outlaws. Much of this work diminished when federal and local agencies improved their law enforcement capabilities shortly after the turn of the 20th century.