WRCK

Chicago, Illinois' WDAI flipped from a Disco format to an Adult-Top 40/Oldies hybrid as "95 W-Rock" with new call letters WRCK.  The very short-lived switch lasted a mere 5 months (May 22 to October 20, 1980) and they then flipped to Top-40 becoming WLS-FM.  The last day of WDAI was spent stunting with a loop of Donna Summer's "Last Dance." The bottom video documents the moment of the actual format change which occurs at around the 27:40 mark.

WNCK

89.5 FM WNCK began in 2002 as a commercial-free Adult Contemporary station run by the owner out of his home in Nantucket, Massachusetts.  They soon entered into an agreement with Boston's WGBH  which simulcast their mix of Classical, Jazz, Blues, Celtic and news programming.  In 2009 they began simulcasting the Classical music of Boston station WCRB.  Since 2020 they have been a Country station branded as "89.5 Quahog Country".  (Quahogs are the largest of the edible hard clams, sometimes called chowder clams.)  I wonder how many non-commercial, full-time Country stations exist in the United States.  Are there any others you can think of?
 

WKBG

WKBG was a Country station in Augusta, Georgia circa the early-to-mid 1990s.
 

WHYA

"Y101" WHYA is a Top-40 station licensed to Mashpee, Massachusetts.
 

WFCR

88.5 FM WFCR is a non-commercial, public radio station broadcasting from the Pioneer Valley area of  Massachusetts.  The license holder is the University of Massachusetts Amherst.  WFCR went on the air in May 1961 and is also heard on 5 translators.  Their call letters stand for Five Colleges Radio.
 

WCCO

The station that would become WCCO signed on in Minneapolis, Minnesota in September 1922 as WLAG.  Financial problems knocked them off the air in 1924 but the Washburn Crosby COmpany (the forerunner to General Mills) had them up and broadcasting a few weeks later with new call letters WCCO.  Today the 50,000-watt clear-channel station airs a News/Talk format featuring mostly local hosts along with a large amount of live sports.  Except for a period between 2007 and 2018, WCCO has been the flagship station of the Minnesota Twins since their first season in 1961.

WASK

1450 AM WASK went on the air in Lafayette, Indiana in 1942.  98.7 FM signed on in 1992 originally as WIIZ and became WASK a few years later.  Today the AM half is a Sports outlet while the FM plays Classic Hits

KTOM

92.7 FM KTOM plays Country music in the Santa Cruz/Monterey/Salinas area of California.  Another KTOM sticker from their previous frequency can be seen here.
 

KPGF

93.7 FM KPGF is an all-80s station licensed to Sun Valley, Nevada near Reno.
 

KLMM / KLUN

"Radio Lazer" are 94.1 FM KLMM and 103.1 FM KLUN. They simulcast a Regional Mexican format in San Luis Obispo, California.
 

KDPT

102.9 KDPT is a 100-watt, low-power FM station in Dos Palos, California.  "Bronco Radio" went on the air in 2001.
 

KAZY

106.7 FM KAZY was a Rock station in Denver, Colorado from 1977 until 1994.

CFRO

Vancouver, British Columbia's community station CFRO "Co-op Radio" went on the air in April 1975.  Programming is divided into four broad categories: Public Affairs, Music, Arts and Third Languages.  About 20% of what's heard on CFRO is in a language other than English or French.  In 2012 they switched frequencies from 102.7 FM to 100.5 FM.

BBC Radio Bristol

BBC Radio Bristol went on the air in September 1970 from Broadcasting House in Bristol, England.  They are now heard on 94.9, 103.6 and 104.6 FM
 

WQKX

"94KX" WQKX is a Top-40 station licensed to Sunbury, Pennsylvania.
 

WBAM

98.9 FM WBAM is a 100,000-watt Country station in Montgomery, Alabama.

Rete Smash Gargano

Rete Smash Gargano plays Contemporary Hit music from Manfredonia on Italy's Gargano peninsula.  They began broadcasting in 1984.
 

Nova Radio

Milan Italy's Nova Radio was founded in July 1976 and was on the air until 1993 when they merged with Radio A to form NovaRadioA.
 

WULM

From 2003 to 2006 WULM was an Oldies station playing a mix of vintage pop and R&B from the 1950s, 60s and early 70s.  They currently air a Catholic format as part of the Radio Maria network (a sticker can be seen here.)  WULM is licensed to Springfield, Ohio.
 

WPMW

88.5 FM WPMW "Radio Cormariae" airs Catholic programming in the New Bedford/Fall River area of Massachusetts.