Starting in the 1930s, WLS was an affiliate of the Blue Network of the National Broadcasting Company (NBC), and as such aired the popular "Fibber McGee and Molly" and "Lum and Abner" comedy programs (both produced at the studios of Chicago's NBC-owned stations, WENR and WMAQ) during their early years. When the Federal Communications Commission forced NBC to sell the Blue Network, WLS maintained its affiliation with the network under its new identity, the American Broadcasting Company (ABC). Under this affiliation, some programs from the network that were not commercially sponsored or which were scheduled to cross the time that WLS and WENR shifted its use of the same frequency (such as baseball or football games) were transferred to air on a third Blue Network/ABC affiliate in Chicago, WCFL. Blue/ABC network broadcasts of addresses by labor leaders were also shifted away from WLS and WENR to WCFL, which was owned at the time by the Chicago Federation of Labor.