65 ILCS 5/10-3-1
The salary to be paid to a policeman in any municipality with 5,000 or more inhabitants but with less than 25,000 inhabitants, shall be not less than $500 per month. The salary to be paid to a policeman in any municipality with 25,000 or more inhabitants but with less than 50,000 inhabitants shall be not less than $550 per month. The salary to be paid to a policeman in any municipality with 50,000 or more inhabitants but with less than 250,000 inhabitants shall be not less than $600 per month.
In this Section 10-3-1 "policeman" means any member of a regularly constituted police department of a municipality, sworn and commissioned to perform police duties, and includes the chief of police, assistant chief of police, chief of detectives, captains, lieutenants, sergeants, plain clothes men and patrolmen. The term "policeman" as used in this Section 10-3-1 does not include any of the following persons: Part time policemen, special policemen, auxiliary police officers , policemen serving initial probationary periods, night watchmen, temporary employees, clerks or other civilian employees of a police department, traffic guards, civilian parking meter and parking facilities personnel or so-called auxiliary police officers specially appointed to aid or direct traffic at or near schools or public functions, or to aid in civilian defense, or special policemen temporarily employed or commissioned as police officers.
65 ILCS 5/10-3-1