Liquid carbon dioxide refrigeration offers a simple, reliable alternative to mechanical transport refrigeration for food delivery trailers operated in an upper midwestern area that could be cost effective when the refrigerant's cost is $87 or less per ton. Operating and ownership costs were compared for both systems. Under the conditions of the study, a carbon dioxide system was more economical than a mechanical refrigeration system when the cost of the liquid carbon dioxide was $87 per ton or less. The study indicated that a fleet of at least ten carbon dioxide refrigerated units is needed to justify use of a storage tank that can accept a 20-ton delivery of liquid carbon dioxide.