The Upper Yough was in the middle of nowhere.
According to Bill Kirby, before the highway was built to Friendsville, the drive from DC took about four and a half hours.
You had to travel down winding gravel roads, often poorly marked, to find your way to the bridge at Sang Run. So the Upper Yough was largely a local phenomenon; paddled by the raft guides in Ohiopyle and the small collection of clubs that made occasional trips.
It was also considered a very difficult run. Few people went down the river without a guide. And if you wanted to find a guide, you either had to know people in the Three Rivers Paddling Club, the Penn State Outing Club, or one of the raft guides in Ohiopyle. So for its first fifteen years, the Upper Yough was the domain of a small, elite group of paddlers.
When Wildwater West Virginia was released, it opened the floodgates to outside boaters.