Those of us who frequently travel across the Great Plains or the Glaciated Plain of the Upper Midwest are usually glad to encounter river valleys, which break the monotony of the flat terrain. In these areas, the primary channel and its tributaries have carved a mosaic of hills, ridges and valleys from the plain, necessitating dips and curves in the route of our journey.
Beyond the topographic relief, these river valleys harbor rich, moist soil, supporting a wide variety of vegetation, offering a sharp contrast from the cropfields, grasslands and sparse woodlands of the adjacent plains. Visually appealing to human travelers, these corridors also attract regional wildlife that utilize them to nest, roost, feed or to escape the harsh conditions on the plain. Indeed, naturalists know that wildlife viewing is significantly more productive along these ribbons of life than it is on the flat terrain that surrounds them; even open-country species tend to congregate near river valleys, a vital source of water and cover.
Of course, river corridors also appeal to those of us who take an interest in regional topography, providing insight into the evolution of Earth's landscape. Unless one is a robotic traveler, oblivious to the environment through which they move, rivers, like mountain ranges and lakes, give us a sense of place and direction, a natural perspective by which to gauge our progress.