Final answer:
The Open Door Policy had a significant impact on the US economy and its relations with China, opening up new markets for American goods and promoting trade and cooperation.
Step-by-step explanation:
The Open Door Policy had a significant impact on the US economy and its relations with China. The policy allowed all countries to trade with China on equal terms, preventing any one country from gaining an advantage over others. This opened up new markets for American goods and allowed the US to increase its economic influence in China. The policy also helped improve US-China relations by promoting mutual trade and cooperation.