Relations between the United States and China can be categorized in at least three main periods: from 1784 through to the 20th century; 1900-1979; and post-1970s. The first American merchant ship, the Empress of China, visited Canton (Guangzhou as it became known) in 1784, starting more than 100 years of trade when the United States sought to exploit China as a market for exports and source of cheap raw materials, such as tea, porcelain, cotton and silk, as well as opium. Several American merchants involved in what was called the Old China Trade became the nation's first millionaires.
The Opium Wars between Britain and China led to the 1842 Treaty of Nanking and, in 1844, the Treaty of Wangxia, in which U.S. President John Tyler sought to give American merchants the same trade privileges as the British and other foreign powers in China. The Treaty of Tianjin in 1860 gave the United States the right to station military and trade legations in Beijing, along with Britain, France and Russia.
The Californian Gold Rush of 1848-1855 saw a steep increase in the amount of Chinese immigration to the United States, many offering "coolie," manual labor in the mines or on the Transcontinental Railroad. But in the economic downturn that followed the Civil War (1861-1865), the Chinese were widely blamed for depressed wage levels, prompting the first restriction on free immigration in U.S. history with the Chinese Exclusion Act of 1882.
In 1899, John Hay, the U.S. Secretary of State, wrote to other world powers Japan, Russia, France, Germany, Italy and Britain, asking them to guarantee the territorial integrity of China, known as the "Open Door Policy," which the vested interests of the other nations declined to embrace. America was involved militarily in China in 1900 when it sent 20,000 troops to lift a siege of the foreign legations in Beijing during the Boxer Rebellion, in which Chinese rebels massacred hundreds of Christian missionaries, railroad engineers and diplomats, as well as Christian Chinese. When the international forces defeated the rebels, the Chinese government was forced to pay compensation and make further concessions to the foreign powers, which contributed to the collapse of the Qing Dynasty and the establishment of the Chinese Republic.
Into the 20th century, the Chinese government remained weak, leading to, in 1931, Japan's invasion of Manchuria. In 1937, President Franklin D. Roosevelt ordered aid to be sent to assist the Chinese government of Chiang Kai-shek. The U.S. and China were effectively allied following Japan's attack on the U.S. fleet at Pearl Harbor in December 1941. American-educated Madame Chiang Kai-shek toured the United States to rally support for her husband's government, resulting in Congress amending the Chinese Exclusive Act.
Immediately after the end of World War II, China was thrown into civil war, as Mao Zedong's Communist party battled for power against Chiang. After the failed peace efforts of U.S. General George Marshall, Chiang's Nationalists were in long-term retreat, driven from the Chinese mainland, where Mao established the People's Republic of China in 1949, while the Republic of China only held power on Taiwan.
Relations deteriorated over the next 25 years, as the two countries supported opposing sides in the Korean War (1950-1953) and the Vietnam War (1955-1975). Not until 1972, and the "Ping Pong Diplomacy," visit of President Richard M. Nixon to Beijing was there a signifcant warming in relations between America and China. The break in relations between China and the Soviet Union offered the U.S. an opportunity to influence the global balance of power during the Cold War. Finally, the United States officially recognized the People's Republic of China in 1979.
Cooperation continued until 1989, when Chinese students and pro-democracy demonstrators were killed by troops in Tiananmen Square. From 1992 to 1999, Taiwan spent $20.6 billion on U.S. arms, which made China increasingly suspicious of American motives. Numerous Chinese casualties in the terrorist attacks on New York and Washington on September 11, 2001, caused Beijing to make a public statement that they will openly support the war against terrorism.
By 2010, the U.S. and China were respectively the world's two biggest economies, providing massive markets for each other. Relations re-focused on trade. According to the U.S.-China Business Council, American exports to China has grown to $91.9 billion by 2010.