This chapter provides an overview of past and current US trade policy, as well as a primer on the rationale for trade policy. The twenty-first century saw an increased liberalization of international trade, a trend which influenced future domestic agricultural policy. Trade barriers that harm a country often lead to it retaliating in the form of imposing countervailing import restrictions or subsidizing their exports. Trends suggest continued growth for US exports and imports, a continuing trade deficit with Canada, economic development and growth in Mexico, and a continued trade surplus with Mexico. Canada and Mexico continue to be the top agricultural export markets for the United States. Mexico and Canada reached separate bilateral North American Free Trade Agreement agreements on market access for agricultural products, eliminating most tariffs over 15 years, except for those affecting trade in dairy, poultry, eggs, and sugar.