Trains run from Harlem every 2–7 minutes during rush hour, and take approx.

Harlem station opened on February 27, 1983 as part of the 7.9-mile extension of the West-Northwest Route from Jefferson Park to River Road.

Where the previous Kennedy stations were all designed by Skidmore, Owings and Merrill (SOM) to be aesthetically similar in appearance, stations on the O'Hare Extension beyond Jefferson Park were designed by four different firms in a variety of architectural styles.

The Harlem station, the only one designed by SOM, shares a similar boxy, open design of the previous 1970 Kennedy Extension (and the 1969-built Dan Ryan stations), except the newer Harlem station has an enclosed platform canopy where the support frame was designed on the highway median walls, thus providing an unobstructed platform, free of column supports.

An almost identical canopy frame was also employed at the Cumberland station, however, it was designed another architectural super-giant, Perkins + Will.