Hillside is a village in Cook County, Illinois, United States. As of the 2020 census it had a population of 8,320.

The community had its first significant residential growth during the 1920s when additional farmland was split up and sold. In the 1920s, there were substantial holdings obtained by St. Domitilla Roman Catholic Church and Mater Dolorosa Seminary. These institutions were formerly surrounded by open space, but following World War II, when Hillside’s population quadrupled (from 1,080 to 2,131) between 1940 and 1950, then surged to 7,794 in 1960, it was submerged in a wave of residential building. Hillside Retail Mall, a pioneering regional shopping area, was next to the just finished Congress Expressway in 1956. Soon after, a Holiday Inn, Hillside Theaters, the High Point Tower office structure, and the industrial park on Fencl Lane surrounding the center.

Hillside Retail Center’s heyday was brief due to the construction of newer, bigger malls and shopping complexes in the 1960s. The mall’s deterioration was unaffected by changes to the exterior look of the building, its tenants, or its ownership. The majority of the mall was razed in 1997 to make room for a large auto dealership.