The modern history of China is a story of misery, a country ruled by a dynasty system inherited with thousands of years of glory but was tragically swept off her feet by vicious foreign powers happened to have embraced technology revolution, applied to naval force and military weaponry and adopted an expansionist foreign policy based on colonialism. More than half the world was victimized by that colonialism, China despite of her size and rich culture had been a victim as well. China was nearly completely conquered and divided by the 'eight foreign power'. Taking the U.S. as the example to follow, Chinese people tried to transform herself through revolution, but not as lucky as the Americans, the Chinese people faced intervention and invasions from the Western powers and her belligerent neighbor Japan.
It turned out that the U.S. had developed the Monroe doctrine (1823 - ) opposing foreign intervention in a weak nation (intended for west hemisphere initially). Extending from the Monroe philosophy, the U.S. considered to her interest to adopt the 'One China' policy in dealing with trades and diplomatic affairs with China. The U.S. opposed the other powers' approach of carving up China into pieces as their 'controlled' territories enjoying unfair trade privileges such as no tariffs. The U.S. took the initiative (Secretary John Hay, 9-6-1899) to request Russia, England, France, Germany, Italy and Japan to respect China as one nation and allow her to administer her own trade rules in China. This is known as 'Open China' policy. Its real impact beyond enforcing an orderly trade system in China was that it had also forced all the foreign powers in China to respect 'One China' and yielded to her sovereignty rights (for example tariff collection) over her own land, ports etc. Although, Japan later broke out her ambition to conquer China, John Hay's 'Open China' policy (declared effective on 3-20-1900 later reissued to all embassies in Beijing on 7-3-1900 when Chinese box rebellion drew military interference from the foreign powers, the foreign powers later occupied Beijing on 8-14 and John Hay issued another declaration on 10-22-1900 ) was essentially the 'One China' policy beneficial to China as well as to the U.S., forcing the foreign powers to show constraints towards China and to each other.
Fast forward, President Richard Nixon visited China on 2-21-1972, first US presidential visit to China since the communist PRC was established in 1949. The U.S. intended to be friend with the communist China during the Cold War against the Soviet Union. The U.S. signed the Shanghai Communiqué (1972) in which 'One China' policy was pledged, specifically, the Mainland and Taiwan being one China. The formal recognition of PRC did not occur till 1979 during Jimmy Carter's administration, but the 'One China' policy has since become the foundation of US-China relation followed by all US Administration therafter. The 'One China' policy has benefitted the U.S. in defeating the Soviet Union making her the only superpower in the world and it was beneficial to China for gaining entry to the US led world economy as well as obtaining steady economic development for nearly four decades. The collapse of the Soviet Union and moving a billion Chinese people above poverty line could be directly attributed to the 'One China' policy.
Now China is marching to be a great nation through her persistent hard work focusing on economic development. It is understandable that the U.S. feels being threatened in her world dominating position. However, as a nation achieved her superpower status under a constitution-based governing system believing in justice and fairness, she can not trash the values that she believed in and evolved to. The world has witnessed and embraced globalization not likely to be reversed by any unilateral action. The earth is facing the threat from nuclear proliferation and environmental challenges, no nation can maintain a superpower status forever at the expense of the Earth or without the cooperation of the world. The world must be managed in 'Harmony' not driven by 'Hegemony'. Realistically, the U.S. must maintain 'One China' policy not just for China's historical mandate but also for the security of the U.S. and the entire world.
The real issue between the U.S. and China is the balance of trade which is the result of many factors but not ideology. As stated in the opening, there is no perfect political system and there is possible workable alternative system, China is pursuing her own and the U.S. must evolve her system to deal with challenges. To deal with trade issues, 'One China' policy is the bedrock for stability for China, the U.S. and the world. Abandoning 'One China' policy leads to chaos not only in China, in Asia but also disaster in the rest of the world. China has become a major manufacturer and market place for the entire world. China must remain stable as one China for maintaining world order and world survival. Realizing such, the U.S. should never doubt her 'One China' policy which benefitted her and the world in the past and will continue benefiting her and the world in the future.