Oak Forest is a suburban city about 24 miles (39 km) south/southwest of downtown Chicago in Bremen Township in Cook County, Illinois, United States. The population was 27,962 at the 2010 census.
The origins of present-day Oak Forest begins with a railroad whistle stop on the Chicago Rock Island and Pacific Railroad near the present day intersection of 159th Street (US Route 6) and Cicero Avenue (Illinois Route 50) which primarily served area dairy farmers. By the 1880s this particular area of timber was being referred to as the "Oak Forest" due to its abundance of oak trees. A section of the former "Cooper's Grove Road" paralleling the railroad track from 66th Court to 167th Street in Tinley Park became known as "Oak Forest Avenue," because it was the road from the Village of Bremen/New Bremen (now Tinley Park) that lead to this "Oak Forest."In the 1930s, there were some efforts made to rename the community "Arbor Park." The proposed name did not gain much momentum, but the name did become memorialized in the name of the Arbor Park School District 145. In 1947, with a population of 1,618, the residents voted to incorporate as the Village of Oak Forest. It was reincorporated as a City in 1971.