The Digital Archive of Newark Architecture provides access to a a few hundred digitized maps of Newark and New Jersey available both at the Littman Library and on the Web. They can be accessed via the archive webpage Maps.
This collection includes Sanborn maps originally created for assessing fire insurance liability in urban areas of the United States. These maps contain detailed information on towns and buildings from 1867 to 1970. Littman Library houses 1930 edition of the Sanborn maps of Newark and also provides access to digitized and made available online Sanborn maps of other places in New Jersey.
In addition to Sanborn maps there are a few other important sets of historical maps: Atlases of Newark and New Jersey of 1806-1915 , 1872, and 1911-1912, Robinson Atlas of Newark (4 volumes published in 1926-28), as well as links to historical maps at Rutgers and Princeton Universities, as well as at Newark and New York Public Libraries.
There is also a large selection of USGS, zoning, tax, economic development, and other maps of the area available via the archive website. To access some of those listed on the page Maps in the Littman Library & Newark Public Library you will need to login using your UCID.