See the Government Documents Library Guide: Trade: U.S. & International for trade information.
Bureau of Economic Analysis: International Economic Accounts: Balance of Payments (International Transactions); Trade in Goods and Services; International Services; International Investment Position; Operations of Multinational Companies (U.S. direct investment abroad, Foreign direct investment in the U.S.); etc.
Census Bureau: International Programs: The U.S. Census Bureau conducts demographic, economic, and geographic studies of other countries. For over 60 years, the Census Bureau has performed international analytical work and assisted in the collection, processing, analysis, dissemination, and use of statistics with counterpart governments in over 100 countries.
The Library of Congress: Country Studies Collection: Electronic versions of 80 books that present a description and analysis of the historical setting and the social, economic, political, and national security systems and institutions of select countries throughout the world.
U.S. Department of State: U.S. Bilateral Relations Fact Sheets: Publications listed include facts about the land, people, history, government, political conditions, economy, and foreign relations of independent states, some dependencies, and areas of special sovereignty.