Complex sentence: By 1971, the road was completed between the Garden State Parkway and I-80, at which time it received the Route 20 designation; the rest was cancelled in 1978 due to feared community disruption.
Split into simpler sentences: By 1971, the road was completed between the Garden State Parkway and I-80, at which time it received the Route 20 designation. The road was cancelled between I-80 and the current northern terminus of Route 20 in 1978 due to feared community disruption.