A Decade of Shipment Tonnage and Value Summaries
The U.S. Maritime Administration has produced a summary of annual tonnage and values for shipments moving through groups of ports across U.S. Customs Districts. The file includes a list of the individual ports included in the 38 unique Custom Districts. The summary statistics are available by year from 2003 to 2013.
Link to dataset: http://catalog.data.gov/dataset/piers-shipping-information-u-s-waterborne-foreign-trade-by-u-s-custom-districts-c6440