Dartmouth can refer to several places, but the most prominent are:

• Dartmouth College is a private Ivy League research university located in the rural town of Hanover, New Hampshire, USA. It is situated in the Upper Valley along the Connecticut River in New England

• Dartmouth, Devon is a historic town and civil parish in the English county of Devon, situated on the western bank of the estuary of the River Dart along the English Channel in southwestern England. It is known for its yachting, boatbuilding, and historic sites like Dartmouth Castle and the Britannia Royal Naval College

• Additionally, there is a town named Dartmouth in Massachusetts, USA, named after the English Dartmouth, and a Dartmouth area in Nova Scotia, Canada, with historical ties to the UK Dartmouth

If you mean Dartmouth College, it is in Hanover, New Hampshire. If you mean the town of Dartmouth, it is in Devon, England.