 Here, the passes through Mercersburg, Greencastle, and Waynesboro.PA 16 heads east through the South Mountain range, where it heads into Adams County and passes through Carroll Valley before coming to the Maryland border.PA 16 intersects several roads including PA 456 in Cove Gap, PA 75 and PA 416 in Mercersburg, PA 995 in Upton, US 11 and Interstate 81 (I-81) in Greencastle, PA 316 and PA 997 in Waynesboro, and PA 116 in Carroll Valley.