...the Westinghouse/Group W-owned TV stations WJZ-TV in Baltimore and WBZ-TV in Boston switched to CBS, dumping their longtime affiliations with ABC and NBC, respectively.
It all started in 1993. After acquiring the rights to the NFC from CBS, Fox sought to upgrade
their affiliate lineup through station group deals, most notably with
New World Communications, a company who owned mostly CBS affiliates (inherited from Storer
Broadcasting) in key NFC markets. This led to more group deals involving
such companies as Scripps and most notably, Group W (Westinghouse), who
ended up purchasing CBS the next year. This major shakeup elevated Fox
to the position of the fourth major TV network in the U.S. and sustained
the growth of Fox Sports. The first of the New World stations (WJW-TV in Cleveland and WDAF-TV in Kansas City) switched on September 12, 1994, with the majority of the others switching on December 11 and 12.
After New World announced their
deal, CBS began wooing longtime ABC affiliates
WXYZ-TV (channel 7) in Detroit (originally an ABC owned-and-operated station, or "O&O," from its sign-on in 1948
until 1986) and WEWS (channel 5) in Cleveland to replace New World-owned WJBK-TV (channel 2) and WJW-TV (channel 8) in their respective markets. Both are owned by the E.W. Scripps
Company, and as part of the renewal of their ABC affiliations, Scripps
agreed to switch some of its other network affiliates. Included were
KNXV-TV in Phoenix, WFTS-TV in Tampa (both were losing Fox to New World
stations in their markets), and WMAR-TV in Baltimore, which would
Westinghouse felt betrayed by ABC after over 45
years of loyalty. They had been shopping around for a groupwide
affiliation deal, but the Scripps/ABC deal pushed them proceed faster.
Eventually, Group W struck a deal with CBS to switch all five of its TV
stations. Existing affiliates KDKA-TV in Pittsburgh and KPIX in San
Francisco began carrying CBS network programming in full in the fall of
1994 (Group W had been known for preempting network programming for
local shows). KYW-TV in Philadelphia had to wait until September,
however, and I'll explain why when the time comes.
In Cleveland, WJW-TV on channel 8 simply swapped affiliations with WOIO
on channel 19. However, in Detroit, CBS struggled to find a new
affiliate. Former Fox-outlet WKBD (channel 50) was out of consideration,
since it was owned by Viacom and slated to become a charter O&O of
the upcoming UPN network. CBS couldn't come to a deal with NBC-affiliate
WDIV (channel 4), and the other major independent stations did not want
to join the network, either. CBS had negotiated with WADL (channel 38),
but walked out after its owner began to make unreasonable demands. With
the date for WJBK's switch quickly approaching, CBS ended up purchasing
low-rated WGPR-TV on channel 62 from a group of African-American
Masons, changing the its call letters to WWJ-TV (the former calls of
WDIV until 1978, since both had been co-owned with WWJ radio sometime
during their history). The sale was met with controversy, however. WGPR
is commonly acknowledged to be the first American TV station ever owned
by African-Americans, therefore, a minority-owned group sued to block
CBS' purchase of the station. A judge ruled on behalf of CBS in 1996 and
the deal proceeded. Channel 62 had the weakest signal of any station in
Detroit, but CBS significantly upgraded its facilities to become the
strongest signal in Detroit. However, this and an advertising campaign featuring Bill Cosby didn't help the network's
ratings in the city, which plunged as part of the switch, and WWJ-TV
remains the lowest-rated of the major network stations in Detroit.
Read more about the network affiliation switches on the Encyclopedia Anyone Can Edit (Wikipedia).