The North American Free Trade Agreement (NAFTA) entered into force on January 1, 1994, establishing a free trade area as part of a comprehensive economic and trade agreement among the United States, Canada, and Mexico. Currently, the United States is renegotiating the agreement. However, repeated threats by President Trump to abandon NAFTA and other actions by the Administration as part of ongoing efforts to "modernize" NAFTA have raised concerns that the United States could withdraw from NAFTA. Although some U.S. agricultural sectors support NAFTA renegotiation and efforts to address certain outstanding trade disputes-regarding milk and dairy products, potatoes, some fruits and vegetables, and wine-many continue to express strong support for NAFTA and oppose outright withdrawal. Possible disruptions in U.S. export markets and general uncertainty in U.S. trade policy also continue to be a concern for U.S. food and agricultural producers. Similar concerns have been raised by some in Congress who have oversight authority on industry and trade activities and who continue to monitor and conduct hearings on the ongoing NAFTA renegotiations. Trade under NAFTA provides an important market for U.S. agricultural producers and a broader choice of food products for U.S. food processors and consumers. Canada and Mexico are the two largest U.S. agricultural trading partners (combining imports and exports), accounting for 28% of the total value of U.S. agricultural exports and 39% of U.S. imports in 2016. Under NAFTA, U.S. agricultural trade with Canada and Mexico has increased significantly. Agricultural exports rose from $8.7 billion in 1992 to $38.1 billion in 2016, while imports rose from $6.5 billion to $44.5 billion over the same period. Adjusted for inflation, growth in the value of total U.S. agricultural exports and imports with its NAFTA partners has increased roughly threefold, growing at an average rate of 5-6% annually. To date, comprehensive quantitative analysis of a possible U.S. NAFTA withdrawal focused exclusively on agricultural markets is not yet available. This report looks at the potential economic effects to agricultural markets of a possible U.S. NAFTA withdrawal assuming the application of most-favored-nation (MFN) tariffs on traded agricultural products instead of the current zero tariff (i.e., duty-free trade) for selected agricultural products. MFN rates generally reflect the highest (most restrictive) rates that World Trade Organization (WTO) members can charge each other on imported goods and services. In general, the application of MFN tariffs on U.S. agricultural imports would likely raise prices both to U.S. consumers and other end-users, such as manufacturers of value-added food products. MFN tariffs on U.S. agricultural exports would, in turn, likely make U.S. products in those markets less price-competitive and more costly to foreign buyers, which could result in reduced quantities sold. Given that certain agricultural products dominate U.S. trade with Canada and Mexico-such as meat products, grains and feed, and processed foods-these products could become more costly and less competitive as MFN tariffs are imposed and other trade preferences are removed under a NAFTA withdrawal. This could result in reduced market share for U.S. products in these markets. Other potential trade impacts under a U.S. withdrawal from NAFTA could include (but are not limited to) higher prices for imported products from Canada and Mexico, reductions in agricultural imports that compete with U.S. products, disruption of integrated supply chains, general market disruption and uncertainty, economic impacts to some agricultural-producing states (both positive and negative), and a decrease of future negotiating leverage of the United States (e.g., to review and resolve disputes regarding a range of non-tariff barriers to trade).