Answer:
As a specific policy with respect to China, Open Door Policy's first advances were made by the United States in the Open Door Notes of September-November 1899. In 1898, the United States had become a power in East Asia by acquiring the Philippines, and when the distribution of China by the European powers and Japan was imminent, the United States felt that its commercial interests in China were being threatened. US Secretary of State John Hay sent notes to the major powers (France, Germany, the United Kingdom, Italy, Japan and Russia), asking them to formally declare that they would defend the territorial and administrative integrity of China and that they would not interfere with the free use of the Chinese ports located within their spheres of influence in China.
In response, each nation evaded Hay's request, taking the position that they would not commit until the others agreed. During this period there was a strong economic tension. However, in July 1900, Hay announced that each nation had agreed at first. Despite the treaties made since 1900 referred to the Open Door Policy, the competition between the powers for special concessions within China for the rights of railways, mining, loans, ports of foreign trade and so on, continued in a constant way.
In 1902, the United States protested the Russian meddling in Manchuria after the Boxer Rebellion as it was a violation of the Open Door Policy. When Japan replaced Russia in South Manchuria after the Russo-Japanese War (1904-1905), the Japanese and American governments committed to maintaining a policy of equity in Manchuria. Financially, the American efforts made to preserve this policy led in 1909 to the formation of an international banking consortium through which all the loans made for the construction of the Chinese railways would be agreed; this led in 1917 to another exchange of notes between the United States and Japan in which there were renewed certainties that the policy would be respected, but also that the United States recognized Japanese special interests in China (the Lansing-Ishii Agreement). The Open Door Policy was later weakened by a series of secret agreements (1917) between Japan and the Allies, since all German possessions in China were promised to Japan after the successful conclusion of World War I.
The growing neglect of the Policy was one of the main reasons for the convening of the Washington Conference (1921-1922) in Washington, D.C. As a result, China's integrity and independence were reaffirmed through the Open Door Policy.
The capture of Manchuria by the Japanese (1931) and the creation of Manchukuo contributed to the end of the Open Door Policy.
At the end of World War II, China's position as a sovereign state was recognized, and all special concessions and unequal treaties were abolished, except for the unequal treaties signed with Russia. However, with the coming to power of the Communist Party of China, the policy was rejected until 1978 when Deng Xiaoping undertook to adopt policies that promoted foreign trade and economic investment.