A major New Jersey Historical Resource is online thanks to Princeton University Library providing access to their collection of Sanborn Maps. According to their press release:
“Each town or city link leads to a town/city website that lists each individual sheet, grouped by year. Clicking on the individual sheet brings up its high-resolution digital image. Copyright restrictions prevent us from showing online images of post-1922 maps — but even those are listed on these websites and can be viewed in person in our department’s reading room in Firestone Library. If the sheet or year is not represented, we don’t have it. A good way to get an idea of which sheet you need to see is to start with an "overview" sheet, if one is provided in the list.
All the Sanborn records are also available by searching in Princeton University Library’s online catalog. There is one record for each city/town/year. A url in that record will also bring you to the town/city’s website. One easy way is to browse the maps in a subject search, using a phrase like "maps—new jersey".
For those of you NewJerseyans who have never looked at a Sanborn fire insurance map: Do so now, for you’ve been missing out on a truly fabulous resource for tracking the historic development of your own community! Your own home or place of business may be on the map!”
You can view the maps here.