Radio Station WTOP began as WTRC New York in 1926, relocating to Mount Vernon, Virginia in 1927 as WTFF, then changing calls to WJSV shortly thereafter, moving to DC in the mid-'30s and changing calls to WTOP in the '40s...
Recent changes at 1500 AM: On January 4, 2006, WTOP moved its all-news format to 103.5 FM (formerly WGMS-FM, which moved to 104.1 FM) and the WTOP-AM call letters were moved to Frederick, Maryland's 820 AM.
1500 AM became WTWP-AM (ironically "Washington Post Radio") until September 20, 2007, when it changed to WWWT-AM ("3WT") with a talk radio format.
The WTOP-AM call letters were retired in 2007, when 820 AM became a simulcast partner of WTWP-AM 1500.