Open Door Policy
The Open Door Policy is a concept in foreign affairs, which usually refers to the policy in 1899 allowing multiple Imperial powers access to China, with none of them in control of that country. As a theory, the Open Door Policy originates with British commercial practice, as was reflected in treaties concluded with Qing Dynasty China after the First Opium War (1839–1842). Through the acquisition of the Philippine Islands, and when the partition of China by the European powers and Japan seemed imminent, the United States felt its commercial interests in China were threatened. U.S. Secretary of State John Hay sent notes to the major powers (France, Germany, Britain, Italy, Japan, and Russia), asking them to declare formally that they would uphold Chinese territorial and administrative integrity and would not interfere with the free use of the treaty ports within their spheres of influence in China. The open door policy stated that all European nations, and the United States, could trade with China.
In reply, each nation tried to evade Hay's request, taking the position that it could not commit itself until the other nations had complied. However, by July 1900, Hay announced that each of the powers had granted consent in principle. Although treaties made after 1900 refer to the Open Door Policy, competition among the various powers for special concessions within China for railroad rights, mining rights, loans, foreign trade ports, and so forth, continued unabated.
Technically, the term "Open Door Policy" can be only referred to as before the founding of the People's Republic of China in 1949. Regarding China's international trade policy introduced after Deng Xiaoping took office, it is termed as China's policy of opening up to the outside world. Although the Open Door is generally associated with China, it was recognized at the Berlin Conference of 1885, which declared that no power could levy preferential duties in the Congo.
Open Door Principle
In 1902, the United States government protested that Russian encroachment in Manchuria after the Boxer Rebellion was a violation of the Open Door Policy. When Japan replaced Russia in southern Manchuria after the Russo-Japanese War (1904–1905) the Japanese and U.S. governments pledged to maintain a policy of equality in Manchuria. In finance, American efforts to preserve the Open Door Policy led (1909) to the formation of an international banking consortium through which all Chinese railroad loans would agree (1917) to another exchange of notes between the United States and Japan in which there were renewed assurances that the Open Door Policy would be respected, but that the United States would recognize Japan's special interests in China (the Lansing-Ishii Agreement). The Open Door Policy had been further weakened by a series of secret treaties (1917) between Japan and the Allies, which promised Japan the German possessions in China on successful conclusion of World War I.
The "Open Door" was a principle, not a policy formally adopted into a treaty or international law. It was invoked or alluded to but never enforced as such. Starting with the Japanese seizure (1931) of Manchuria and the creation of Manchukuo, however, the Open Door principle was broken with impunity and increasing frequency. 
Open Door Policy in modern China
In China's modern day economic history the Open Door Policy refers to Deng Xiaoping's visits to the Special Economic Zones (SEZ) in 1992 and his belief that to modernize China's industry and boost its economy it needed to welcome foreign direct investment. After his visit Chinese industry shifted heavily to encourage and support foreign trade & investment. It can be argued this was the turning point that truly started China on the path to being 'The World's Factory'.
- Economy of the People's Republic of China
- Economic history of China (Pre-1911)
- Economic history of China (1912–1949)
- Open door policy (business)
- Philip Joseph, Foreign diplomacy in China, 1894-1900
- Sugita (2003)
- Sugita (2003)
- Sugita (2003)
- Lawrence, "Open Door" 
- Esthus, Raymond A. "The Changing Concept of the Open Door, 1899-1910," Mississippi Valley Historical Review Vol. 46, No. 3 (Dec., 1959), pp. 435–454 JSTOR
- Hu, Shizhang (1995). Stanley K. Hornbeck and the Open Door Policy, 1919-1937. Greenwood Press. ISBN 0-313-29394-5.
- Mark Atwood Lawrence, “Open Door Policy”, Encyclopedia of the New American Nation, (online).
- McKee, Delber (1977). Chinese Exclusion Versus the Open Door Policy, 1900-1906: Clashes over China Policy in the Roosevelt Era. Wayne State Univ Press. ISBN 0-8143-1565-8.
- Otte, Thomas G. (2007). The China question: great power rivalry and British isolation, 1894-1905. Oxford University Press. ISBN 978-0-19-921109-8.
- Sugita, Yoneyuki, "The Rise of an American Principle in China: A Reinterpretation of the First Open Door Notes toward China" in Richard J. Jensen, Jon Thares Davidann, and Yoneyuki Sugita, eds. Trans-Pacific relations: America, Europe, and Asia in the twentieth century (Greenwood, 2003) pp 3–20