<Tr> <Th> Existed </Th> <Td> 1958--1964 </Td> </Tr> <P> Originally planned as far back as 1929, the Mid-County Expressway was later proposed by the Pennsylvania Turnpike Commission as the "Chester Extension" of the Pennsylvania Turnpike in 1954 . After the advent of the Interstate Highway System, the project was transferred to the Pennsylvania Department of Highways to be built as part of the system, designating it first as Interstate 495, and later as Interstate 480, as I - 76 was designated as I - 80S at the time . The present - day I - 476 designation was assigned on February 6, 1964, when I - 80S was renumbered as I - 76 . </P> <P> The road received its nickname from a 1958 location report indicating various proposed geographic configurations of an expressway through Delaware County with lines of various colors on a map . The "blue route" through the Crum Creek valley won out over other contenders, which included a more easterly "red route" and "yellow route" and a more westerly "green route". </P> <P> As one of the most controversial Interstate Highways in Pennsylvania, construction of I - 476 began in 1967, but was not completed until 1991 between MacDade Boulevard (Exit 1) and Interstate 76 (Exit 16), and until 1992 between Germantown Pike east / Chemical Road (Exit 19) and Interstate 276 / Pennsylvania Turnpike (Exit 20), due to litigation between the Pennsylvania Department of Transportation and several communities in the road's path over environmental concerns . However, the section of Interstate 476 (south end of I - 476) between I - 95 and MacDade Blvd . (Exit 1) was opened in 1987, but signage labeled it as a route "To MacDade Blvd" until 1991 when I - 476 / The Blue Route was opened between Exits 1 and 16, and connected with the short existing section of roadway dating back to 1979 from Exit 16 - Exit 19 . </P>

Why do they call 476 the blue route
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