What was a key reason for the USA advocating an 'open door' policy towards China in the late 19th century?

The rationale behind the United States advocating for an 'open door' policy towards China in the late 19th century was primarily driven by the desire for access to the vast Chinese market for American goods. This policy, articulated in a series of notes sent by U.S. Secretary of State John Hay in 1899, aimed to ensure that all countries would have equal trading rights in China and prevent any single power from monopolizing the market.

During this period, Western powers were carving out spheres of influence in China, leading to fears that American businesses would be shut out of one of the largest and most potentially lucrative markets in the world. The U.S. government believed that by promoting an open door policy, American economic interests could flourish, thereby ensuring that U.S. manufacturers and exporters could compete fairly for trade with China. This overarching goal was essential for sustaining the U.S. economy, which was increasingly reliant on international trade.

The context of this policy underscores the economic motivations of the United States rather than militaristic or colonial ambitions, as seen in other global interactions of the time. As such, this focus on gaining trading access illustrates the strategic economic interests that the United States sought to prioritize in its foreign relations with China during that era.