I grew up in Plainfield in the 50’s. It’s tragic what’s happened to New Jersey since.
The biggest change over the past 20 years has been the outflow of Republican voters as well as the migration of Clifford Case/Millicent Fenwick Republicans to the Democrats. As GOP voters leave suburban areas they are replaced by Democratic "latte liberals" from NYC (see Ridgewood, Montclair, Westfield) and affluent LEGAL immigrants who buy into the "Republicans are for white, Christians" only mythology. In the southern part of the state, you have seen a huge inflow of state employees into places like Burlington County, to say nothing of blue collar (union) voters from Philly who still remain loyal to the Democratic Party. This is why the counties that face Philly have gone Dem in every national election since 1988.
You know this state is hopeless when the last Republican elected to the Senate (Clifford Case) was first elected when my father was delivering the Star Ledger back in the 1950s, and last reelected in the 1972.