Answer: Very Bad.
Explanation:
The United States were a staunch supporter of Chiang Kai-shek who was the leader of mainland China as a Nationalist from 1928 to 1949.
In 1949, the Communists under Mao Zedong defeated Chiang and forced him to flee to Taiwan.
The US were wary of Communism and determined not to let it spread and so did not recognize the new Chinese state. They recognized Taiwan as China and even gave China's seat in the UN Security Council to Taiwan.
Various incidents highlighted how bad relations were between the 2 nations. Some of them included; the Korean War, the Taiwan Strait Crises, the Vietnam war and the Tibetan Crisis.
During the Korean War, China and the United States went against each other with China attacking United Nations forces which were mostly made up of Americans and the United Nations counter attacking. The conflict was so bad that General MacArthur called for a nuclear strike on China.
The Taiwan Strait Crisis almost saw the Nationalists who were allied to the US go to war with the Communists.
The Vietnam war saw the United States and the Chinese again supporting different sides of a conflict when the Chinese supported North Vietnam and the Americans, the South.
However during the late 60s, Soviet Russia and Communist China saw a thaw in their relationship as both subscribed to varying degrees of Communism. This saw minor border clashes but more importantly it convinced President Nixon to reach out to China. From 1967 onwards, the two countries began to negotiate a path forward which saw the games Ping Pong Diplomacy of 1971 where an American Ping Pong team came to play against a Chinese one.
