In 1977, a reorganization took place within the ISP and left it with 5 Divisions: State Police, Criminal Investigation, Internal Investigation, Support Services and Administration Additionally, each division within the Illinois State Police provides specific services. In 1967, the black and white patrol cars were replaced with a basic beige color scheme. 1948 saw a temporary end to the use of motorcycles for patrol.

In 1930, the Chryslers were replaced by Ford Model A's. In 1927, the first patrol cars (Chrysler coupes) were purchased and issued only to Sergeants as they were deemed to be District Commanders. The Illinois State Police was officially created in 1922 and the primary function of the agency was the protection of the roads from damage by overweight vehicles. On June 24, 1921, the 52nd General Assembly of the State of Illinois authorized the Department of Public Works and Buildings to hire a 'sufficient number of State Highway Patrol Officers to enforce the provisions of the Motor Vehicle Laws.' This new group of law enforcement officers were known as the State Highway Maintenance Police.

Illinois motorcycle plates