Final answer:
John Hay's Open Door Policy aimed to open up trade with China, ensuring all interested powers had free access to Chinese ports and a level playing field in commerce. This policy favored American interests by allowing American businesses to trade more efficiently and with a competitive edge in the Chinese market, based on the quality and cost of American goods.
Step-by-step explanation:
The Open Door Policy, introduced by U.S. Secretary of State John Hay, was an initiative aimed at opening up trade with China. Hay's Open Door Notes, sent in 1899, encouraged powers with interest in China, such as Japan, England, Germany, France, and Russia, to maintain free access to all treaty ports within China and to not impose unfair tariffs or trade restrictions. This policy was supported by the American Asiatic Association and benefited the United States by providing American businesses an equal opportunity to trade in China without the limitations of spheres of influence and also with an advantage due to the lower cost and better quality of American goods.
Responding to concerns over the partition of China by foreign powers and seeking to prevent the United States from being excluded from the lucrative Chinese market, Hay's notes essentially advocated for an equal trade environment where no single power could dominate. While the Open Door Policy was accepted by some countries with hesitation, Hay declared it as the guiding principle in trade relations in China, setting the foundation for significant economic benefits to the United States over other nations.