1922 Encyclopædia Britannica/Police
POLICE (United States).—An interesting recent development as regards police in the United States has been the establishment in certain states of a state police, sometimes called constabulary. This body acts under state rather than local authority, is usually organized on a military basis, is widely distributed for patrol duty, but can be quickly mobilized for emergencies. Such forces are of special service for protecting life and property in country districts, made accessible to robbers and assassins by the introduction of the automobile. Since the adoption of national prohibition much of their time has been spent in suppressing illegal liquor traffic.
The largest state police force is that of Pennsylvania, consisting in 1920 of 415 officers and men. It was organized in 1905 somewhat after the model of the Canadian Northwest police. It is composed of five troops with posts in different parts of the state. Detachments are sent out to the 40 stations and from the stations small patrols operate in every direction. The posts and stations are in constant communication, and help can be rushed immediately to any point. They are empowered to make arrests for any violation of the law; at the same time they act as fish and game wardens and as fire patrols. When practicable they cooperate with the local authorities in preserving order. In some states their powers are somewhat restricted; in New York they cannot enter a city to suppress a riot unless so ordered by the governor or on request of the mayor with the approval of the governor. But in any state they may pursue a criminal and arrest him anywhere. In Pennsylvania applicants for appointment who have served in the army, navy or militia are given preference. The recruit serves a probation period of four months and makes a study of the state laws. The period of enlistment is two years. Another type of state police is seen in South Dakota, where the sheriffs and deputy-sheriffs form a state constabulary “for the purpose of detecting crime, apprehending criminals, suppressing riots, preventing affrays, and preserving and enforcing law and order throughout the state.” In Idaho all state, county and municipal officers form a state constabulary under the direct control of the commissioner of the department of law enforcement. A third type is seen in the Massachusetts District Police, consisting of a detective and an inspection department. Appointments are made by the governor and his council. At the governor's command they suppress disorder anywhere in the state. They do not maintain a patrol. In 1920 a state police, or constabulary, was maintained in 12 states: Massachusetts, Texas, Connecticut, Pennsylvania, Nevada, New York, South Dakota, Michigan, Idaho, New Mexico, Tennessee, and West Virginia. At that time several other states were considering the establishment of such forces.
A special committee on state and metropolitan police, appointed by the American Institute of Criminal Law and Criminology, in a report submitted in 1920 urged active cooperation “in educating the people, and especially the Legislatures of their respective states, with respect to the nature, methods, and value of a state police force.”
See this committee's report, “Metropolitan and State Police,” in the Journal of the American Institute of Criminal Law and Criminology, vol. XL, No. 3 (Nov. 1920). An excellent account of the largest and best organized of the state police forces is given by Kathenne Mayo in Justice to All: The Story of the Pennsylvania State Police (1917), with an introduction by Theodore Roosevelt.