ancient bridle-path of the pack-horse age. On the greater routes westward the introduction of wheeled vehicles necessitated some changes; now and then the deep-worn passage-way was impassable, and detours were made which, at a later day, became the main course. Here, where the widened trail climbed a steeper "hog-back" than usual, the cart-drivers made a roundabout road which was used in dry weather. There, where the old trail wound about a marshy piece of ground in all weathers, the cart-drivers would push on in a straight line during dry seasons.
Thus the typical pioneer road even before the day of wagons was a many-track road and should most frequently be called a route—a word we have so frequently used in this series of monographs. Each of the few great historic roads was a route which could have been turned into a three, four, and five track course in very much the same way as railways become double-tracked by uniting a vast number of side-tracks. The most important reason for variation of routes was the wet and dry seasons; in the wet season advantage had
