Yeah, the Hyannis rotary -- the traffic circle -- is a major Cape Cod landmark. It's a big one and has businesses all around it. There's even a small mall now, though I don't know whether it was there in 1977.
Here's a map, with the airport marked to the right. The rotary is that circle in the middle.
https://maps.google.com/maps?q=Barn...arnstable+Municipal+Airport,+Hyannis,+MA&z=17
This location is the transportation center of Cape Cod -- you can catch a bus to locations all over the Cape and beyond, or an airplane to Boston or New York City -- both scheduled flights and air taxi. Exactly what companies were providing service has varied over the years, but most of the time there's something. There are motels and restaurants where you could meet somebody. State route 28 provides a good chance to catch a ride with somebody, no matter where you're going. And there were lots of people catching rides with other people in 1977.
If she really was trying to get to anywhere on Cape Cod, that was a good place to catch a second ride. If she was meeting somebody, meeting at a restaurant on the rotary would be convenient from almost anywhere. If she really was running away, it was a good location to leave from.
She had only been missing for a couple of years when we moved to New England, but people were still talking about it. There have always been rumors across rural and suburban eastern MA that there was a rogue cop or trooper who was a serial rapist/killer who would attack women under the guise or helping them, and that this is why several such missing persons cases received so little attention.
