Derived from 2011 Automatic Identification System (AIS) broadcast returns. Each vessel count per aliquot block represents the number of vessels traveling through the block during the year of 2010. An aliquot measures 1/16 of a full OCS leasing block or 1200 x 1200 meters. Only areas where BOEM publishes Official Protraction Diagrams will contain the aliquot AIS counts, therefore, large areas of inland state waters may be missing aliquot AIS counts. The data has also been clipped so that any aliquot that touches land has been deleted so that the user can discern the location of the coastline. Vessel type breakdowns can be viewed using the ID tool or by downloading the data.  To download the data please click the following links for the Atlantic portion and the West Coast portion of the data.