Editing WRR (FM) (section)

===Unusual callsign===
While most radio stations in Texas have four-letter [[call sign]]s beginning with a K, this station has three-letter callsign beginning with a W. Many stations going on the air in the early 1920s received three-letter call signs. The AM station with which WRR-FM had once been partnered dates back to 1921. WRR (AM) was the first licensed radio station west of the Mississippi and among the earliest in the country.

With the introduction of land-based U.S. radio station licensing in late 1912, it had been the practice to assign call signs starting with "K" in the west and "W" in the east.<ref>[https://earlyradiohistory.us/kwtrivia.htm "K/W Call Letters in the United States"] by Thomas H. White.</ref>  (Ship-based stations were just the opposite.) The original boundary line was located along the Texas-New Mexico border, and it wasn't until the shift in early 1923 to the [[Mississippi River]] that new stations going on the air in Texas received K instead of W call signs.  However, existing stations were allowed to keep their non-conforming callsigns, which included such stations as WRR, [[WBAP (AM)|WBAP]] in [[Fort Worth]] and [[WOAI (AM)|WOAI]] in [[San Antonio]]. When WRR put the FM station on the air in 1949, the FCC allowed it to use the same call sign, plus the "-FM" [[suffix]].

After the AM station was sold and its callsign changed to KAAM, WRR-FM dropped the no longer required "-FM" suffix from its call sign, effective May 15, 1978.<ref name="hc" />