New Jersey Paperback Series
Publisher: Rutgers University Press
The spines of these titles appear to have only been marked for numbers 1-6. The series may have continued past 1963, but it's difficult to tell, as the series is not indicated anywhere on the wrappers for these titles. The name of the series comes from an ad for Rutgers University Press in PW.
Rutgers to Publish Paperbacks on New Jersey, PW, Apr. 17, 1961, at 34 (announcing publication of three titles of New Jersey interest: (1) The Old Farm by Andrew Mellick Jr. on May 1, (2) Exploring the Little Rivers of New Jersey by James Cowley & Margaret Cowley on June 15, and (3) Stories of New Jersey by Frank R. Stockton on June 26).