PC*MILER Shortest Routes represent distances and driving routes that a vehicle would take to minimize total distance traveled while still following a reasonable route. For instance, Shortest Route mileage and routes will also avoid truck-restricted roads and, in some cases, may favor a beltway rather than traveling directly through a city.
However, because the goal of the Shortest route type is to minimize total distance, there is not much emphasis on taking major highways. This could mean avoiding long loops of a major interstate by exiting the interstate to take a shorter more direct route. For example, going from Baltimore, MD, to Richmond, VA, a Practical Route will take I-495 around Washington, DC; a Shortest Route will take US-1 through Washington, DC, in order to minimize the distance traveled.