Dave said:WSBT-TV in South Bend Indiana has been owned by Schurz Communications since it signed on in 1952, & had CBS as the primary affiliation the entire time they've been on the air. I however don't know if WSBT-AM has been owned by Schurz since it signed on in 1922, or if they acquired it in 1925. I haven't been able to find out about the ownership of WNSN 101.5 FM South Bend throughout the years.
Also in South Bend Indiana, Michiana Public Broadcasting has owned WNIT TV since its sign on in 1974.
For Chicago, I'll mention WCIU. Weigel Broadcasting has owned WCIU-TV since its signon in 1964, & continues to own the station today, but expanded nationally with This TV & MeTV diginetworks. All other stations have changed owners at some point in history, with the exception of WGN-TV, WTTW, & WYIN on the TV side. WYIN has been owned by Northwest Indiana Public Broadcasting since its signon in 1987 on 56, but they originally had planned to acquire the WCAE license instead, which that license was for channel 50, & the original non-commercial license, & station off the air. Had Newsweb not changed the non-commercial allocation to the WGMI license, which was for channel 56, channel 56 would not have seen the light of day in Northwest Indiana. So other than a license change, as WYIN, it's been under the same owner since it's sign on.
WSBT-AM and WNSN have both been owned by Schurz since they started. WSBT-AM started in 1921 as an experimental station and was licensed in 1922. WNSN was experimental in 1943 and became a licensed FM after that.
Schurz has also owned the South Bend Tribune since it started in 1872