Early Roads Established by Wagons

In the early days when transportation horsepower was limited to the number of horses pulling a wagon, we find that the route from some Point A to another Point B did not always follow the route of the  shortest distance.  This observation is true for  hilly country.  Wagon routes found the route of least effort, but maybe more distance, while modern highways found the shortest distance, using more effort.  Better wheels and bigger engines on transport vehicles made all this change occur.
So, this begs the question of how wagon routes were chosen to get from a Point A to a Point B in hilly country before the car, the train.
First off, wagon drivers did not want to pull up a hill only to give it back again by going down the other side of a hill.  In fact, going downhill was often a chore because wagons did not have adequate brakes and so the wagon would tend to run up on the horses.  As an aside, one old trick was to chain a log to the wagon at the top of a hill; dragging it downhill helped with braking.
Okay, so no up a hill only to go back down the other side.  So what was the most obvious way to select a route?  They looked for creek beds, active or dry and they ran their wagon roads up the valley of the drainage.
There was another advantage to the selection of a creek drainage as the wagon road.  It provided the most opportunity for watering the horses.