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."

-- Feb. 21-28, 1972: Then US President Richard Nixon made a formal visit to China, with a China-US joint communique released in Shanghai on Feb. 28. The joint communique, also called the Shanghai Communique, was the first of its kind between the two countries.

-- Jan. 1, 1979: China and the United States officially established diplomatic relations at the ambassadorial level. The United States announced it would cut all "diplomatic relations" with Taiwan, withdraw its troops and terminate the US-Taiwan Mutual Defense Treaty on Jan. 1, 1980.

-- Jan. 28-Feb. 5, 1979: Chinese Vice-Premier Deng Xiaoping paid an official visit to the US at the invitation of US President Jimmy Carter. The visit, the first by a Chinese leader to the United States, opened a new chapter in the history of China-US relations. On Jan. 31, the two sides signed a bilateral technological cooperation agreement and a cultural agreement.

-- Oct. 26-Nov. 3, 1997: Chinese President Jiang Zemin paid a state visit to the United States. On Oct. 29, the two countries issued a joint statement, establishing the goal, the principles and the directive policy of building a constructive strategic partnership in the 21st century. The leaders of the two countries also agreed to establish a regular consultation mechanism between the defense ministries of the two countries.

-- June 25-July 3, 1998: US President Bill Clinton made a state visit to China, during which the two countries issued three joint statements on South Asia, the inspection protocol to the Biological Weapons Convention and the issue of anti-personnel mines.

-- April 6-14, 1999: Chinese Premier Zhu Rongji made an official visit to the United States. Zhu and US President Bill Clinton issued a joint statement on China's accession to the World Trade Organization.

-- Nov. 19-21, 2005: US President George W. Bush paid a visit to China, during which he held talks with Chinese President Hu Jintao. The two leaders exchanged views in an in-depth way on China-US relations and regional and international issues of common concern. They agreed to expand common understanding and deepen mutual trust in order to carry forward in an all-round manner the constructive and cooperative relations between the two countries in the 21st century.

-- April 18-21, 2006: Chinese President Hu Jintao visited the United States. The two sides agreed that China and the United States had extensive and important common strategic interests and were not only mutual stakeholders, but should also be constructive collaborators. They agreed that a sound bilateral relationship was of strategic significance for safeguarding and promoting peace, stability and prosperity in the Asia-Pacific region and the world at large.

-- Aug. 7-11, 2008: US President George W. Bush attended the opening ceremony and associated activities of the Beijing Olympic Games.

-- Nov. 15-18, 2009: US President Barack Obama paid a formal visit to China, during which he held talks with Chinese President Hu Jintao.

-- Jan. 18-21, 2011: Chinese President Hu Jintao paid a state visit to the United States, during which he met with US President Barack Obama. The two sides issued a joint communique on bilateral ties.