1. Free trade area: duty-free domestic trade, but differences in external tariff levels. Some opponents of free trade support free trade theory, but oppose free trade agreements as applied. Some opponents of NAFTA see the agreement as a significant prejudice to the people in the public domain, but some arguments are in fact opposed to the specifics of state-run trade and not to free trade itself. For example, it is argued that it would be wrong to leave subsidized U.S. corn in Mexico under NAFTA at prices well below production costs (dumping), as they have a ruinous effect on Mexican farmers. Indeed, such subsidies run counter to the theory of free trade, so that this argument does not run counter to the principle of free trade, but to its selective implementation. [Citation required] In the first two decades of the agreement, regional trade increased from about $290 billion in 1993 to more than $1 trillion in 2016. Critics are divided on the net impact on the U.S. economy, but some estimates amount to $15,000 a year for the net loss of domestic jobs as a result of the agreement. In Britain, free trade became a central principle practiced by the repeal of the maize laws in 1846. The League of The Anti-Corn Law was sponsored by the Anti-Corn League. Under the Nanjing Treaty, China opened five contract ports for world trade in 1843.
The first free trade agreement, the Cobden-Chevalier Treaty, was put into force in 1860 between Great Britain and France, resulting in successive agreements between other European countries.  A free trade agreement is an agreement between two or more countries to facilitate trade and remove trade barriers. The aim is to eliminate tariffs completely from day one or over a number of years. Free trade economists believed that trade was the reason why some civilizations prospered economically. Thus, Smith highlighted the intensification of trade as a reason to prosper not only for Mediterranean cultures such as Egypt, Greece and Rome, but also for Bengal (East India) and China. The great prosperity of the Netherlands, after having dered Spanish imperial domination and pursued a free trade policy, made the free trade/mercantilist conflict the main economic issue for centuries. Free trade policy has been fought over the centuries with mercantilist, protectionist, isolationist, socialist, populist and other policies. The world has achieved almost more free trade in the next round, known as the Doha Round Trade Agreement. If successful, Doha would have generally reduced tariffs for all WTO members. Nevertheless, a certain level of protectionism is the global norm.
Most developed nations maintain controversial agricultural tariffs. From 1820 to 1980, average tariffs on manufactured goods in twelve industrialized countries ranged from 11 to 32%. In developing countries, average tariffs on industrial products are about 34%.  American economist C. Fred Bergsten developed bicycle theory to describe trade policy. In this model, trade policy is dynamically unstable, constantly moving towards either liberalisation or protectionism. To prevent cycling from falling off the wheel (the disadvantages of protectionism), trade policy and multilateral trade negotiations must constantly move towards greater liberalization.