What was the main purpose of the United States' Open Door Policy?

The purpose of the Open Door Policy was to give all nations equal rights when trading with China, according to the Encyclopaedia Britannica. It was initiated by the United States and aimed to both enhance global trade and to promote China's welfare and sovereignty.

Open Door policy, statement of principles initiated by the United States in 1899 and 1900 for the protection of equal privileges among countries trading with China and in support of Chinese territorial and administrative integrity. The statement was issued in the form of circular notes dispatched by U. S. Secretary of State John Hay to Great Britain, Germany, France, Italy, Japan, and Russia. The Open Door policy was received with almost universal approval in the United States, and for more than 40 years it was a cornerstone of American foreign policy in East Asia.