The Legend is not from the 1960's. The Native Americans have many stories of encounters with them.
"The Bigfoot figure is common to the folklore of most Northwest Native American tribes. Native American Bigfoot legends usually describe the creatures as around 6-9 feet tall, very strong, hairy, uncivilized, and often foul-smelling, usually living in the woods and often foraging at night. Native American Bigfoot creatures are almost always said to be unable to speak human languages, using whistles, grunts, and gestures to communicate with each other. In some stories, male Bigfeet are said to be able to mate with human women. In some Native stories, Bigfoot may have minor supernatural powers-- the ability to turn invisible, for example-- but they are always considered physical creatures of the forest, not spirits or ghosts."
Now some parts of legends are not true but most are based on some facts. We are so civilized and smart we think we know it all.