New Cumberland is a borough in the easternmost region of Cumberland County, Pennsylvania, United States. New Cumberland was incorporated on March 21, 1831. The population was 7,507 at the 2020 census. The borough is noted for its historic downtown which includes landmarks like the historic West Shore Theater, Borough Park and the yearly Apple …New Cumberland is a borough in the easternmost region of Cumberland County, Pennsylvania, United States. New Cumberland was incorporated on March 21, 1831. The population was 7,507 at the 2020 census. The borough is noted for its historic downtown which includes landmarks like the historic West Shore Theater, Borough Park and the yearly Apple Festival, which gathers hundreds of vendors and thousands of visitors.