Old Dominion Freight Line is a national carrier that provides direct service to more than 45 U.S. states. The firm has a staff of more than 12,000 employees in its entire network and has a fleet of over 5,000 tractors and nearly 14,000 trailers. It offers a full range of export and import services and has interchange agreements with all major steamship lines. In addition, Old Dominion Freight Line provides assembly and distribution services. The firm uses an interactive voice response, which is a computerized telephone system that provides telephone-based access to shipping information. Old Dominion Freight Line has been operational for more than 70 years and maintains a location in Portland, Maine.