The North Central Service (NCS) is a Metra commuter rail line running from Union Station in downtown Chicago through northwestern and far northern suburbs to Antioch, Illinois.

[3] While Metra does not explicitly refer to any of its eleven routes by colors, the NCS' timetable accents are lavender, a shade of purple.

120, made all stops along the North Central Service from Antioch to Washington Street, then switched to the Milwaukee District North Line's tracks at a diamond near Prairie Crossing station, made stops at Libertyville and Lake Forest, and then ran express to Union Station.

The CN assumed ownership of this route on September 7, 2001, when it absorbed the Wisconsin Central Railroad ("WC").

Prior to the start of NCS, the last passenger service on this route ended in January 1965, when the Soo Line discontinued the overnight Chicago-Duluth Laker.

The North Central Service serves O'Hare International Airport, but with a limited number of trains.

As of April 2021, NCS service is limited to rush hours in the peak direction only–towards Chicago in the morning and towards Antioch in the afternoon.

On weekends, there were 16 hourly round trips serving the same stations, with no service north of O'Hare Transfer.