5 Popular Songs that Mention Cape Cod says this:

Old Cape Cod
Cape Codders consider this 1957 tune the unofficial Cape Cod Anthem. Some even credit it with putting the Cape on the map and helping to establish Cape Cod as a major tourist destination. The lyrics are actually a poem written by Boston-area housewife Claire Rothrock, who vacationed on Cape Cod with her family. According to Patti Page, Rothrock approached her at a Boston nightclub where she was performing and presented the poem. Page fell in love with it, and the rest is history!

Each verse of the song ends with the line "You're sure to fall in love with old Cape Cod."