Which private policing agency is historically recognized for private security work in 19th-century America?

• A. Pinkerton Detective Agency
• B. The Pinkerton Agency
• C. U.S. Secret Service
• D. Professional Security Corporation

Answer: (B)

Private policing in 19th-century America relied heavily on private detective firms hired by businesses to protect property, investigate crimes, and manage labor unrest. The agency founded by Allan Pinkerton rose to prominence as the leading private security and detective organization of that era. The name most commonly cited in historical references is The Pinkerton Agency, which is why it’s the best choice here. The U.S. Secret Service is a federal agency, not private, and Professional Security Corporation isn’t the historically recognized firm associated with 19th-century private security. The Pinkerton Detective Agency is basically the same organization, but the wording used in the question points to The Pinkerton Agency.