Plymouth is an incorporated borough in Luzerne County, Pennsylvania, United States, west of Wilkes Barre, on the Susquehanna River. Prior to its incorporation in 1866, it was part of Plymouth Township, established in 1769 by the Susquehanna Company and claimed by Connecticut based on the charter of that colony. The Pennamite-Yankee War was fought in the environs.
Plymouth is situated in the rich hard coal fields of Pennsylvania. Coal was first shipped in 1807. In the past, the chief products of its industrial establishments included mining drilling machines, miners' squibs, silk hosiery, and lumber products. In 1890, Plymouth's population was 9,340; its population peaked in 1910 at 16,996. The population was 5,951 at the 2010 census.