Lots of Deer in NJ too. I think more than in Pennsylvania
I hear tell that the environment created by plantiung lawns and shrubs instead of native woodland actually does support more Deer per square mile, so you might be right. the other thing is that New Jersey is so restrictive about firearms, and so generally set against hunting that these animal populations tend to get out of control quickly.
According to a hunting Safety instructor I know, the town of Princeton NJ actually brought in hired guns under the guise of "Biologists" to thin their Deer herd rather than let hunters do it and make use of the animals.
It's a shame I think.