PA 340 begins at an intersection with PA 462 in the community of Bridgeport in East Lampeter Township, Lancaster County, heading east on two-lane undivided Old Philadelphia Pike. The road runs through areas of homes and businesses, passing south of the Harrisburg Area Community College Lancaster Campus before briefly forming the border between the city of Lancaster to the north and East Lampeter Township to the south. Farther east, the route heads between industrial parks to the north and neighborhoods to the south before coming to an interchange with the US 30 freeway that does not have a ramp from westbound US 30 to PA 340. Past this interchange, PA 340 runs through less dense areas of residential and commercial development with some farm fields. At this point, the route enters the Pennsylvania Dutch Country of eastern Lancaster County, which is home to many Amish farms and businesses catering to tourists. The road enters the community of Smoketown and intersects the northern terminus of PA 896 to the south of Smoketown Airport. The route crosses Mill Creek and continues east to the community of Bird-in-Hand, where it passes under Amtrak's Keystone Corridor.