Police officers have used motorcycles—primarily for the enforcement of traffic laws and as escort vehicles—since the early 20th century. Chief August Vollmer of the Berkeley Police Department is credited with organizing the first official police motorcycle patrol in the United States in 1911. However, several police forces around the country reported using motorcycles as patrol vehicles earlier. Harley-Davidson credits Detroit, Michigan as being the first purchaser of police motorcycles in 1908. The police department in Evanston, Illinois also purchased a belt-driven motorcycle for its first motorcycle police officer in 1908, and the Portland, Oregon Police Bureau had a police officer who used his personal motorcycle to patrol the city as early as 1909.