WLS is a Class A station broadcasting on the clear-channel frequency of 890 kHz with 50,000 watts of power using a Harris DX-50 transmitter. The station's daytime groundwave service contour covers portions of five states while at night its signal routinely reaches 38 states via skywave. WLS participates in the Emergency Alert System's primary entry point network, serving that function for northern Illinois and western Indiana. The station's programming is also available to listeners in the Chicago metropolitan area with an HD Radio receiver via a simulcast on the HD2 subchannel of sister station WLS-FM.