An interstate shipment begins when it starts its course to another state or has been delivered to a carrier for such transportation and ends when the shipment has reached the ultimate destination originally intended by the party that controls the movement. All transportation from beginning to end is transportation in interstate commerce. The details of the interstate movement of goods (e.g., the number of carriers involved in the movement, billing arrangements between the carriers, or whether there is actual physical continuity of the movement) are irrelevant in as far as the determination that the movement is interstate commerce.