The Coal and Iron Police was a private police force in the US state of Pennsylvania that existed between 1865 and 1931. It was established by the Pennsylvania General Assembly but employed and paid by the various coal companies. The origins of the Coal and Iron Police begin in 1865. Law enforcement in Pennsylvania at that time (and until 1905) existed only on the county level or below; an elected sheriff was the primary law enforcement officer (for each county). The case was made by the coal and iron operators that they required additional protection of their property. Thus the Pennsylvania State Legislature passed State Act 228. This empowered the railroads to organize private police forces. In 1866, a supplement to the act was passed extending the privilege to "embrace all corporations, firms, or individuals, owning, leasing, or being in possession of any colliery, furnace, or rolling mill within this commonwealth". The 1866 supplement also stipulated that the words "coal and iron police" appear on their badges. A total of over 7,632 commissions were given for the Coal and Iron Police.
The first Coal and Iron Police were established in Schuylkill County, Pennsylvania, under the supervision of the Pinkerton Detective Agency. Although the Coal and Iron Police nominally existed solely to protect property, in practice the companies used them as strikebreakers. The coal miners called them "Cossacks" and "Yellow Dogs". For one dollar each, the state sold to the mine and steel mill owners commissions conferring police power upon whomever the owners selected. Common gunmen, hoodlums, and adventurers were often hired to fill these commissions and they served their own interests by causing the violence and terror that gave them office. The coal and iron police worked with the Pinkertons, particularly with a labor spy by the name of James McParland, to suppress the Molly Maguires.