In Rye NH, in the 1940s-50s lived a man named John ... he was very slender and quite tall and everyone in town referred to him as "Long John"! Why he was so called is no longer recalled in local lore.
Long John lived on the Rye end of a *very *long road which ran from Portsmouth to Rye. All the locals called the Rye end of Sagamore Road "Long John Road." Just before the turn of the millenium the "Powers That Be" gave up their intransigence and named the southerly section of Sagamore Road as "Long John Road."
Cap K (a sweetie) and SWMBO (a smart, handsome and forebearing lady by the way) were taken to get their first taste of fried clams via Long John Road! They enjoyed them.