Dauphin is a borough in Dauphin County, Pennsylvania, United States. The population was 796 at the 2020 census. Dauphin’s ZIP code is 17018. It is portion of the Harrisburg–Carlisle Metropolitan Statistical Area.

Dauphin is located on the western edge of Dauphin County at 40°22′00″N 76°55′52″W / 40.366687°N 76.931168°W / 40.366687; -76.931168, on the east bank of the Susquehanna River. The house at the river’s edge is alluvial floodplain, but Dauphin sits at the head of a narrow valley amongst two mountains, at the mouth of Stony Creek. The valley amongst the two mountains is called Stony Valley, which contains the villages of Singersville and Ellendale Forge. This section along the Susquehanna River is a gateway from the southeastern plains into the Appalachian Mountains and the north-central allocation of the state. Berrier Island is in addition to located at Dauphin.

Dauphin is in the middle of Middle Paxton Township, which comprises mountains and valleys south of the confluence of the Susquehanna and Juniata rivers. From south to north, the mountains in the township are Blue Mountain, Second Mountain, Third or Stony Mountain, and Peters Mountain. The eastern ends of these valleys are generally undeveloped declare game lands and protected watershed.

U.S. Routes 22 and 322 pass through the borough as a four-lane expressway, close to the Susquehanna River, with full admission from Pennsylvania Route 225 at the west subside of town and as soon as westbound admission from the east halt of town. US 22/322 leads south 8 miles (13 km) to the middle of Harrisburg and northwest 7 miles (11 km) to Duncannon. PA 225 leads north higher than Peters Mountain 9 miles (14 km) to Halifax.