(a) Motor carriers. Every motor carrier (of property or passengers) shall make a designation for each State in which it is authorized to operate and for each State traversed during such operations. Every motor carrier (including private carriers) operating in the United States in the course of transportation between points in a foreign country shall file a designation for each State traversed.

(b) Brokers. Every broker shall make a designation for each State in which its offices are located or in which contracts will be written.