<Tr> <Td> KERO (23) </Td> <Td> NBC (1953 - 1984) CBS (1984 - 1996) ABC (1996--present) </Td> <Td> ABC (1996--present) </Td> <Td> Originally operated on channel 10 from 1953 to 1963 . </Td> </Tr> <Tr> <Td> Baltimore, Maryland </Td> <Td> WMAR (2) </Td> <Td> CBS (1947 - 1981) NBC (1981 - 1995) ABC (1995--present) </Td> <Td> ABC (1995--present) </Td> <Td> </Td> </Tr> <Tr> <Td> Birmingham, Alabama </Td> <Td> WBRC (6) </Td> <Td> NBC (1949 - 1954) CBS (1954 - 1961) ABC (1961 - 1996) </Td> <Td> Fox (1996--present) </Td> <Td> Only station in the United States to be a primary affiliate to all Big Four networks over the course of its history . </Td> </Tr> <Tr> <Td> Boston, Massachusetts </Td> <Td> WNAC / WNEV / WHDH (7) </Td> <Td> CBS (1948 - 1961; 1972 - 1995) ABC (1961 - 1972) NBC (1995--2016) </Td> <Td> Independent (2017--present) </Td> <Td> </Td> </Tr>

In the 1940s the two television networks most competitive in the creation of television were