By 1830 the American push for commercial reciprocity was bringing results, and discriminatory barriers to trade were falling rapidly. In fact, the Western world was entering a period of widespread commercial liberalism. Leading British statesmen were pushing for reciprocity and for the general elimination of customs duties. The British Corn Laws were repealed in 1846, the Navigation Acts were abolished three years later, and the Cobden-Chevalier Treaty of 1860 with France greatly stimulated free trade in Europe. During this period the meaning of free trade was expanded to encompass the elimination or reduction of all tariffs on goods.
With a few exceptions, the United States participated in the trend that it had helped to promote. Tariff rates generally dropped after 1832. The "Black Tariff" of 1842 was highly protective, but the Walker Tariff of 1846 dropped the rates, and the Tariff of 1857 pushed them even lower. In his 1845 report, Secretary of the Treasury Robert Walker identified "reciprocal free trade" with low duties and argued that such a policy "would feed the hungry and clothe the poor of our fellow-men throughout all the densely peopled nations of the world." The Democratic Party pushed for lower duties, and the platform of 1856 pledged the party to a policy "in favor of free seas, and progressive free trade throughout the world." One of the Democratic Party's main areas of strength was the agricultural South, and farmers opposed protective tariffs because they raised prices on the manufactured goods they purchased. During this period, many large industries wanted protection from foreign competition and the Republican Party favored industry over agriculture.
The United States–Canadian Reciprocity Treaty of 1854 constituted a milestone in this expanded definition of reciprocity, establishing almost complete free trade in natural products between the two countries. It also provided for the joint use of the Atlantic coast fisheries and for reciprocal transit rights in canal systems, the St. Lawrence River, and Lake Michigan.
During this period another version of reciprocity and the open world began to emerge. This was the right and duty of the "Christian nations" to force closed states to trade and to accept the Western system of commercial rights. John Quincy Adams praised the British during the Opium War with China for forcibly upholding the natural right of free commerce among nations. According to Adams, the "righteous cause" of Britain was not opium but the principle of "equal reciprocity." He also hoped that the peace treaty would establish future trade with China "upon terms of equality and reciprocity." Perhaps Adams and others did not necessarily envisage the system of rather unequal treaty relations that developed after the 1840s, but he had completely accepted the idea that the Western nations had the right and duty to force the "backward," or non-Christian, nations to accept the Western presence and systems. During these years, however, the open-door version of reciprocity was still in its infancy, and very limited in its application.
The United States followed Britain in the opening of China and took the lead in opening Japan. In the process, Americans altered the interpretation of reciprocity. As in commercial treaties with Morocco (1836) and Zanzibar (1837), the treaties with Japan (1854) and China (1858) provided unconditional most-favored-nation treatment for the United States in those countries. However, the United States did not give most-favored-nation treatment in return. In addition, China and Japan accorded the United States the privilege of extraterritoriality, which meant that in many cases Chinese and Japanese laws did not apply to Americans. The United States did not grant reciprocal privileges because American officials did not regard reciprocity in "backward" nations as a two-way street. The United States did continue to stress the principle of equality of treatment for all foreign interests.