Naval Support Activity (NSA) Mechanicsburg is an 824 acre naval supply depot in Hampden Township and Cumberland County, Pennsylvania, approximately 7 miles west of Harrisburg, Pennsylvania. The installation consists of 150 buildings with 7.9 million square feet of warehouse space. The base employs about 5,000 civilian and 190 military personnel. The department falls under the umbrella of Navy Region Mid-Atlantic Fire & Emergency Services.