Dozens of stations jumped on that "24-Hour News Channel/Source" bandwagon in the late '80s and early '90s. OTOH, we were very late at 24-hour operations. KNDO went 24/7 in 1996, and so did KCYU-LP (Fox 68). The other three locals still went off the air into the 2000s, and even the 2010s. KYVE would go 24/7 besides two hours of occasional maintenance Monday mornings, in the mid-late '00s, KIMA went 24/7 in 2011, and KAPP finally went 24/7 in 2012 adding World News Now and MeTV 35.2 simulcasts to their late night lineup.
KING-5 was 24/6 in the early '80s, don't know if I mentioned it already. They aired old movies, Marshal Dillon and Alfred Hitchcock overnights, and signed off after the late movie Sunday night/Monday morning. They would later sign off late Sat nights in the early '90s (they preempted SNL to 12:05 due to Almost Live!, airing Friday the 13th: The Series for a few years at 1:30AM). KING went 24/7 when NBC offered Nightside on Saturday nights/Sunday mornings. KOMO was 24/7 in the early '90s as well.