In the 1940s, the term "chain broadcasting" was used when discussing network broadcasts, as the television stations were linked together in long chains along the East Coast. But as the television networks expanded westward, the interconnected television stations formed major networks of connected affiliate stations. In January 1949, with the sign-on of DuMont's WDTV in Pittsburgh, the Midwest and East Coast networks were finally connected by coaxial cable (with WDTV airing the best shows from all four networks). By 1951, the four networks stretched from coast to coast, carried on the new microwave radio relay network of AT&T Long Lines. Only a few local television stations remained independent of the networks.