I've always considered Tom Kean's 1985 landslide victory to be the one against which all other are measured. He won 71% to 24%, carrying virtually every town in New Jersey, including Newark, Camden, and Jersey City. His margin of victory was so large, in fact, that he swept in 4 Republican Assemblymen in heavily Democratic, heavily urban Hudson County (Jersey City, Union City, Hoboken).
Yeah Kean won 60% of the urban vote in that Election. It would be impossible for a Republican to win a state or a US House Seat in Hudson County nowadays. Kean's Governor's Race in 1981 against Jim Florio was close though. I would like to see a map of the 1981 Race but thats not on this site.