A file photo of Xinhua shows China and US pingpong players exchange gifts at the welcome ceremony in Beijing, China for the visiting US pingpong team on April 13, 1971. [Photo/Xinhua]

BEIJING - Chinese President Xi Jinping starts a four-day state visit to the United States Tuesday at the invitation of US President Barack Obama. The following is a chronology of highlights in China-US relations over the past four decades:

-- April 10 - 17, 1971: A US pingpong team visited China, as the first US delegation to receive an invitation to visit China since 1949. The visit led to the restoration of China-US relations which had been cut for more than two decades.

The "pingpong diplomacy" promoted the development of China-US relations and changed international relations. As one comment described it, "the big globe was set in motion by a tiny globe."