The Yellow Line, also known as the Skokie Swift, is a branch of the Chicago "L" train system in Chicago, Illinois. The 4.7-mile (7.6 km) route runs from the Howard Terminal on the north side of Chicago, through the southern part of Evanston and to the Dempster Terminal in Skokie, Illinois, making one intermediate stop at Oakton Street in downtown Skokie. It is the shortest line in the system when not counting the Purple Line during off-peak hours.

At Howard, Yellow Line passengers can transfer to the Purple or Red Lines of the "L". The Yellow Line is the only "L" line that does not go to The Loop and is the only "L" train route that is fully ADA accessible. It is also unique in that it runs in a below-grade trench for part of its length, even though it has no underground portions and does not run in an expressway median. It also includes grade segments and crossings at the western portion of the line. It was built using the tracks of the former Chicago North Shore and Milwaukee Railroad's high-speed Skokie Valley Route.

Extending the line to Old Orchard Mall in Skokie has been discussed. From its original opening in 1925 until 1948, the line had several intermediate stops in Evanston and Skokie, but these stations have long been out of use and dismantled. In June 2010, however, construction began on a new station at Oakton, which opened on April 30, 2012.

Trains operate using the Bombardier-built 5000-series railcars; each train consists of two cars. Average weekday boardings of 1,240 were reported in 2023, making it by far the least-used route in the CTA rail system. Until late 2009, the Yellow Line was operated with the 3200-series cars that were specially equipped with roof boards that, until late 2004, held pantographs (the roof boards remain on cars 3441-3456 to this day even after they were officially reassigned to the Brown Line). Occasionally, the Yellow Line borrows cars from the Red Line when short on cars.

The Yellow Line begins at the Dempster-Skokie terminal located at 5005 Dempster Street in Skokie. A stub track extends north of the station to allow trains to reverse. The line runs south from Dempster-Skokie at street level. After crossing Oakton Street, the Yellow Line turns east and crosses over Skokie Boulevard (U.S. Route 41). After the East Prairie Road grade crossing, the tracks rise to become an elevated route.

At this point, the route passes the Skokie Shops CTA maintenance facility and crosses over the North Shore Channel. After passing over Dodge Avenue, the tracks descend into a trench. The line remains in the trench for about 1 mile (1.6 km), then passes under the Metra Union Pacific North Line and Purple Line tracks to enter Howard Yard. The line then rises to serve the elevated Howard station. A small segment extends south of the station to allow Yellow and Purple Line trains to reverse.

The Yellow Line operates between Dempster-Skokie and Howard daily between 4:45 a.m. and 11:15 p.m. on weekdays, and between 6:15 a.m. and 11:15 p.m. on weekends and holidays. Service frequencies range from six trains per hour during rush hour to four trains per hour during other times.

The Yellow Line originally began as the Niles Center Branch of the old Chicago Rapid Transit Company (CRT). The rapid transit service began as part of the Chicago, North Shore, and Milwaukee Railroad's high-speed Skokie Valley interurban line on a five-mile (8 km) section between Howard Terminal and Dempster Street, Niles Center. It was placed in operation on March 28, 1925.