According to Betty Hill, the famous UFO abductee, at one point in the 20th century an island in the Connecticut River was inhabited by a tribe of small primitive people.
For the space of about three years, people who lived near the river reported seeing prehistoric-looking people on an island that was supposed to be uninhabited. Whenever anyone (including the police) ventured out to the island to investigate the cavemen disappeared.
"It was as though somebody had picked up a group of early cavemen and had set them down on the island in a New England countryside. Planes and helicopters had flown over the area, hoping to get pictures, but these little people - they're not really tiny people, but maybe four feet tall or so - would just take off running at such speeds that no one could even get pictures of them. These prehistoric people would be there one instant, they would start running, and in the next instant, they would just disappear."
Like a lot of classic folklore the particulars of the story are vague. Where did it happen, and when? It's not clear. Betty claims she was told about the cave people by someone else, and didn't remember exactly where the island was, but thought maybe it was someplace near Springfield, Massachusetts.
I'm grateful to Joseph Citro for including this story in his fantastic book Weird New England. Apparently Betty Hill first wrote about the cave people in an article called "Bigfoot in New England." Bigfoot researcher Jack Kewaunee Lapseritis also interviews Betty on this topic in his book The Psychic Sasquatch and Their UFO Connection. That's an amazing title for a book, but it looks like it is out of print. Some copies on Amazon are selling for hundreds of dollars! I guess everyone wants it as much as I do.
To me little cavemen sound suspiciously like faeries or trolls, and those creatures are notoriously hard to pin down. Maybe they were just paying a brief visit from the mythic world to remind us they're still lurking around, even if we can't prove they're really there.