Final answer:
The Open-Door Policy aimed to allow economic expansion and equal trade opportunities for all foreign powers in China, preserve Chinese sovereignty, and avoid exclusive territories or dominant influence by any single nation.
Step-by-step explanation:
The main ideas of the Open-Door Policy of American involvement in China were centered around promoting economic and territorial expansion in China, encouraging equal trade opportunities for all foreign powers. Secretary of State John Hay introduced the policy through a series of circulars known as Open Door notes, with the aim of acquiring China's vast markets for American access and ensuring that all nations could trade with China on equal terms, without any single power gaining dominance. The Open-Door Policy was designed to prevent the division of China into exclusive spheres of influence and to maintain China's sovereignty and territorial integrity while allowing American businesses to thrive in an open market environment.