Xie Yuan, vice-president of the Chinese People's Association for Friendship with Foreign Countries, described the cooperation between his organization and SCI in the past three decades as a "perfect couple".

The two organizations have joined hands in holding two China-US sister cities conferences in the last two years. A third one will be held in November in Nanchang, in East China's Jiangxi province.

Xie noted the expanding relationship at the sub-national levels, such as with organizations like the National Governors Association and State Legislative Leaders Foundation.

US states and provinces have forged stronger bonds with China, with China being a top trade partner and export destination for US states. More US governors and mayors embark on trade missions to China to expand trade and investment ties.

An updated report this year by the Rhodium Group and the National Committee on US-China Relations showed that Chinese investment in the US grew to a record of more than $15 billion in 2015. The investments extend across more than 80 percent of congressional districts.

About 300,000 Chinese students are studying in colleges and universities across the US, accounting for almost a third of all the international students on US college campuses.

Since November 2014, when the two countries announced visa-extension programs, the number of Chinese tourists to the US has soared. About 2.67 million Chinese visited the US in 2015, compared with fewer than 400,000 in 2007. That number is expected to jump to 5 million by 2025, according to Goldman Sachs.

Karen Richardson, US deputy assistant secretary of state for public outreach, praised the partnership between SCI and the Friendship Association for forging a new relationship that promises to build peace and understanding between the two peoples.

"We at the State Department hope that this effort will continue and encourage US and Chinese cities to come together and build on the long legacy of citizen diplomacy and peace-building of the sister-city tradition," she said.

The US sister-city program started in 1956, when then-president Dwight Eisenhower proposed a people-to-people, citizen diplomacy initiative. Originally a program of the National League of Cities, SCI became a separate non-profit entity in 1967 due to the rapid expansion of the program.

Minister Li of the Chinese embassy congratulated SCI on its 60th anniversary, and he said, that according to the Chinese lunar calendar, 60 years represents a full cycle of time, or Samsara in Buddhism.

"We hope to see more sister cities set up between China and US, as well as other countries and the US. More substantial activities and cooperation can come out among sister cities," he said.

Contact the writer at chenweihua@chinadailyusa.com