The DuMont Television Network was one of the world’s pioneer
commercial television networks, rivaling NBC and CBS for the
distinction of being first overall in the United States. It began
operation on August 15, 1946 and aired it’s final telecast on the
6th of August, 1956. The country would be without a fourth major
network until the Fox network was launched in 1986.

Portland’s KPTV channel 27, now channel 12, was an affiliate of
DuMont from September 1953 to September 1955.