President Richard Nixon made the historic first trip by a sitting U.S. president to the People's Republic of China during a time when U.S. relations with the nation were shaky. </br></br> Nixon and Secretary of State William Rogers with Chinese Deputy Premier Li Xiannian during a visit to the Great Wall of China, February 1972.

With the Vietnam War over, President Richard Nixon tried to bridge relations with China while driving a wedge between China's Soviet allies. </br></br> Nixon toasts Zhou Enlai, the Chinese prime minister, during a state banquet in Beijing, February 1972.

President Richard Nixon laid the framework for future U.S. presidents to build stronger relationships with the People's Republic of China. </br></br> Nixon, second right, speaks with Chinese Communist Party Chairman Mao Tse-tung, center, at a meeting in Beijing, China, Feb. 21, 1972.

President Gerald Ford inherited the previous administration's foreign policy and advisers when he took office. Following in Nixon's footsteps, Ford continued the détente policy with China. </br></br> Ford smokes his pipe as he talks with the leader of the Chinese Communist party Deng Xiaoping in Peking, China, December 1975.

President Gerald Ford's December 1975 visit continued to help lessen the tensions between the two countries. </br></br> Ford and Chinese Vice Premier Teng Hsiao-Ping reach for food with their chopsticks during the last banquet of Ford's visit to China, December 1975.

President Jimmy Carter's administration is credited with formally establishing diplomatic relations with the People's Republic of China, set forward by the two previous administrations. </br></br> Carter shakes hands with China's Vice Premier Deng Xiaoping during arrival ceremonies at the White House in Washington, Jan. 29, 1979.

President Jimmy Carter with Chinese Communist leader Deng Xiaoping sign papers to establish formal diplomatic ties between the U.S. and China for the first time since 1949.

President Jimmy Carter's normalization of relations with the People's Republic of China provided both sides with essential tools to help facilitate and promote common objectives; working together on space technology, academic exchanges and consular relations. </br></br>Chinese Deputy Premier Deng Xiaoping and his wife stand with President Carter and first lady Rosalynn Carter at a state dinner in honor of Deng Xiaoping's visit to the United States, Jan. 29, 1979.

President George H.W. Bush toasts with Chinese President Yang Shangkun during a welcoming banquet held in the Great Hall of the People, February 1989. Bush was on a two-day visit to China. </br></br>The president spent 14 months as the U.S. representative to China during the Ford administration and was well liked and respected by the Chinese government.

President George H.W. Bush and his wife, Barbara Bush, wave to crowds of Chinese onlookers after their motorcade made a stop at Tiananmen Square, February 1989. </br></br>Less than two months later, the Chinese government would use their army to suppress peaceful demonstrations taking place in the square. Bush announced the suspension of sales of U.S. arms to China as a protest against the Chinese government's actions.

President Ronald Reagan and President Li of the People's Republic of China stand in front of the Great Hall of People in Beijing, China, 1984.

Chinese Premier Zhao Ziyang and President Ronald Reagan shake hands at the conclusion of their meeting at the Great Hall of the People.

President Ronald Reagan and Chinese Premier Zhao Ziyang during arrival ceremonies on the South Lawn of the White House, January 1984.

President Bill Clinton, right, holds up his hands indicating no more questions as he and Chinese President Jiang Zemin hold a joint press conference, Oct. 29, 1997, in the Old Executive Office Building in Washington. </br></br>It was the first state visit by the president of China to the United States in 12 years and aimed to improve relations over human rights, nuclear proliferation and Taiwan. Clinton confirmed that he agreed to lift a ban on the export of nuclear power technology to China and the two signed the Sino-US Joint Statement following their talks.

President Bill Clinton walks with Chinese President Jiang Zemin to a group photo session with other leaders of APEC countries outside the Great Hall of the Museum of Anthropology in Vancouver, Canada, Nov. 25, 1997.

A remark by President Bill Clinton brings applause from the crowd of students at Beijing University on the last day of his visit to the capital of China, June 29, 1998. </br></br>Clinton was the first president to visit China following the crackdown at Tiananmen Square in 1989. Clinton extended "most-favored nation" status to China and in 2000, granted permanent normal trade relations.

President of the People's Republic of China Jiang Zemin with the President George W. Bush in Shanghai, China, as APEC 2001 gets underway, Oct. 20, 2001.

President George W. Bush and first lady Laura Bush flanked by China's President Jiang Zemin and his wife, Wang Yeping, wave to the media at Bush's Prairie Chapel Ranch, Oct. 25, 2002, in Crawford, Texas. </br></br>In closing statements, President Bush said, "The United States seeks and is building a relationship with China that is candid, constructive, and cooperative. We will continue building this relationship through contacts at many levels in months to come, including a new dialogue on security issues."

President George W. Bush smiles at reporters following a press briefing on his trip to Beijing, China, Nov. 20, 2005, at the St Regis Hotel. Bush spoke to reporters after meeting with China's President Hu Jintao and Premier We Jiabao. </br></br> Bush attempted to leave the room through a door that was locked, which flustered him and he ended up exiting the room behind this wall. He told the press corps, "I was trying to escape. It didn’t work."

President George W. Bush pulls Chinese President Hu Jintao from stepping off the stage during an arrival ceremony at the South Lawn of the White House, April 20, 2006, in Washington. </br></br>Hu, on his first official visit to the U.S. since he took office in 2002, was headed in the wrong direction and President Bush reached out to stop him. In a joint press conference, Bush would declare, "The United States welcomes the emergence of a China that is peaceful and prosperous and that supports international institutions."

On his first ever visit to China, President Barack Obama walks with Chinese President Hu Jintao at Diaoyutai State Guest House, Nov.16, 2009, in Beijing, China. </br></br>Obama was the first sitting president to visit China during his first year in office, during a nine-day, four-nation tour of Asia, signaling his intent to "pivot" foreign policy attention from the Middle East to Asia.

During his eight years in office, President Barack Obama travelled to China three times in an ongoing effort to warm relations between the two countries. </br></br> Obama is welcomed by Chinese President Xi Jinping as he arrives for the APEC Summit banquet at the National Aquatics Center in the Chinese capital, Nov. 10, 2014.

Chinese President Xi Jinping accompanies President Barack Obama to view an honor guard during a welcoming ceremony outside the Great Hall of the People, Nov. 12, 2014, in Beijing, China. </br></br>Hoping not to repeat his first press conference with Jintao, in which the Chinese leader refused to answer questions, Obama pressed Jinping to take questions but received a lecture instead. In 2015, Obama hosted Xi and his wife to a lavish state dinner at the White House, wooing his counterpart with top business leaders and celebrities.

Chinese President Xi Jinping holds the Chinese documents to formally join the Paris climate deal alongside President Barack Obama, as both countries formally join the Paris climate deal, at Ruyi Hall in Hangzhou, China, Sept. 3, 2016. </br></br>The two overcame obstacles, including a debacle over the stairs used to deplane upon Obama's arrival, to sign the agreement in a rare display of harmony. Obama hailed the accord between the world’s two biggest polluters as the "moment we finally decided to save our planet."