Lincoln later hired Pinkerton agents to conduct espionage against the Confederacy and act as his personal security during the American Civil War.

[5] During the labor strikes of the late 19th and early 20th centuries, businesses hired the Pinkerton Agency to infiltrate unions, supply guards, keep strikers and suspected unionists out of factories, and recruit goon squads to intimidate workers.

Historian Frank Morn writes: "By the mid-1850s, a few businessmen saw the need for greater control over their employees; their solution was to sponsor a private detective system.

[17] Among the business's early operations was to safely deliver the newly elected President of the United States, Abraham Lincoln, from Springfield to Washington, D.C., in light of an assassination threat.

Pinkerton detective Kate Warne was assigned and successfully delivered Lincoln to the U.S. capital city through a series of disguises and related tactics that required her to stay awake throughout the entire long journey.

These actions preceded and laid the groundwork for the establishment of the United States Secret Service, which is tasked with serving current and former U.S. Presidents' security to this day.

In 1871, Congress appropriated $50,000 (about equivalent to $1,272,000 in 2023) to the new Department of Justice to form a sub-organization devoted to "the detection and prosecution of those guilty of violating federal law."

[22] Following the strike, Congress took swift action against the Pinkertons and passed the Anti-Pinkerton Act in 1893, which severely curtailed the relationship between the federal government and the agency.

On July 6, 1892, during the Homestead Strike, 300 Pinkerton agents from New York and Chicago were called in by Carnegie Steel's Henry Clay Frick to protect the Pittsburgh-area mill and act as strikebreakers.

Orchard testified (unsuccessfully), under threat of hanging,[26] against Western Federation of Miners (WFM) president Big Bill Haywood, naming him as having hired the hit.

[27] Pinkerton agents were hired to track western outlaws Jesse James, the Reno Gang, and the Wild Bunch (including Butch Cassidy and the Sundance Kid).

In Union, Missouri, a bank was robbed by George Collins, aka Fred Lewis, and Bill Randolph; Pinkerton Detective Chas Schumacher trailed them and was killed.

With less of the labor and criminal investigation work on which Pinkertons thrived for decades, the company became increasingly involved in protection services, and in the 1960s, even the word "detective" disappeared from the agency's letterhead.

[34] In December 2018, Securitas AB issued a cease and desist notice to video game company Take-Two Interactive over the use of the Pinkerton name and badge imagery in Red Dead Redemption 2.

[37][38] In 2020, Matthew Dolloff, an unlicensed security guard contracted through Pinkerton, shot and killed Lee Keltner, a conservative protester, in Denver, Colorado.

Cannon had published a video on YouTube showing the contents of an order received ahead of the release date from a local game store.