Plymouth Rock is the traitional site of disembarkation of William Bradford and the Mayflower Pilgrims who founded Plymouth Colony in 1620, in what would become the United States. There is no contemporary reference to it, and it is not referred to in Bradford's journal Of Plymouth Plantation or in Mourt's Relation. The first reference to the Pilgrims landing on a rock is found 121 years after they landed. The rock is currently located on the shore of Plymouth Harbor in Plymouth, Massachusetts.