The export surge is causing temporary shortages of overseas shipping containers in some parts of the country, says David Letteney of the Steamship Operators Intermodal Committee. One Minneapolis exporter reports he had to bid against more than 50 other companies for containers he used to get easily. Such periodic shortages are normal in a healthy economy because imports don't always flow to the regions where exports originate, Letteney says. What's remarkable is that U.S. trade performance has been so bad over the past decade that there haven't been shortages.