Although all import and export data presented in this report are official Commerce statistics, these data may differ from the data presented by other government agencies and private institutions that cite Commerce as the source for trade data. Possible reasons for these differences are as follows:

• Data in this report include merchandise trade only; other reported data may include services.
• Data are not seasonally adjusted; the values of other reported data may be so adjusted.
• Data are not adjusted on a balance of payments (BOP) basis; the values of other reported data may be so adjusted in line with the concepts and definitions used to prepare national and international accounts.
• Exports and imports may not include all errata because certain errors may not be corrected by Commerce in time to be included in this report.
• Data in this report may be adjusted for errors that are not of sufficient magnitude to be changed in Commerce data.
• The import and export data in this report for 2013-17 have been updated as of February 12, 2018, based on the latest official revisions from the Census Bureau. The merchandise sectors contained in this report are defined by the Commission and may differ from similarly labeled groups from other sources.

The Commission’s staff has prepared "A Note on U.S. Trade Statistics" that is intended to help the public understand the most widely cited figures on the U.S. merchandise trade balance. It begins by defining the underlying trade flows and proceeds to a discussion of the resulting trade balances.