The development and growth of the China-US relationship could be fulfilled through more close local cooperation between sister states and provinces. Grassroots leaders, it seems, tend to be practical and down to earth.

Last week, the most frequent phrase I heard when attending China-US trade and economic exchanges-themed events was "sub-national cooperation". From California's lieutenant governor to the visiting Qingdao mayor and his San Francisco counterpart, to China's top diplomat in San Francisco, they all sang the praises of local collaboration.

Addressing representatives of Chinese enterprises that operate in Northern California on May 18, Lieutenant Governor Gavin Newsom emphasized the important role that regional cooperation has played in fostering strong trade and investment between the Golden State and China.

"Regions will rise and fall together," he said, adding that the influx of Chinese direct investment is "a big part of our economic recovery".

The history of sub-national mechanism can be traced to 2011, when China and the US launched an interagency government team to promote communication and exchanges between American and Chinese regional leaders. The then-US Secretary of State Hilary Clinton and Foreign Minister Yang Jiechi signed a memorandum of understanding supporting US-China sub-national cooperation on Jan 19, 2011.

In the same year, the US-China Governors Forum was established. American governors including California's Jerry Brown, Governor Jay Inslee of Washington, Governor Terry E. Branstad of Iowa, Governor Rick Snyder of Michigan and Governor Kate Brown of Oregon met their Chinese counterparts from Sichuan province, Beijing, Chongqing, and Zhejiang, Shandong and Shaanxi provinces.

The sub-national framework promotes US-China trade and investment, people-to-people exchanges and partnerships and facilitates provincial contacts and regional outreach.

On Sept 22, 2015, President Xi Jinping attended the third China-US Governors Forum themed "Clean Energy and Economic Development" in Seattle, the first stop during his US state visit. He fully affirmed its focus on a low-carbon economy, pointing out that it highly corresponds with the common challenges now facing China, the US and the international community.

Xi stressed that local cooperation plays an important role in developing state-to-state relations. The relationship between countries requires people's support in the end and will eventually serve the people, he said, adding that only local cooperation can best benefit people.

"In the past 30-odd years, China-US relations have benefited from the support of local regions and peoples in the two countries and will still rely on and benefit local regions in the future," Xi said.

"In recent years, China-US local cooperation and exchanges are displaying a new boom. Both sides have established 43 pairs of sister provinces/states and 200 pairs of sister cities," he said.

Investment and trade are the anchors of a practical US-China relationship and cooperation, the president said.

As the central government requires, there are local follow-up actions and policy deployment. Newsom said that the state "is committed to assisting companies and individuals and their business activities in California".

On May 17, Qingdao Mayor Zhang Xinqi led his business delegation executives of 20 world-renowned companies to visit San Francisco. His dual missions on the US trip included sponsoring the Sino-US Regional Economic & Trade Cooperation Forum and an opening ceremony of the Qingdao Center for Business & Commerce USA.

A city famed for its open economy, port and trade businesses, Qingdao is the economic powerhouse of Shandong province. It's also the hometown to international enterprises such as Haier, Hisense and Tsingtao Brewery.

For future development, Qingdao has outlined its "200-year" strategic objectives and is building itself into an international city with a global vision on top of its abundant cultural, marine, tourism and economic resources.

By March, Qingdao had invested in 194 projects in the US with a total value of $9.08 billion, said Zhang, adding that the city was listed as a model city for China-US trade and investment cooperation by the Ministry of Commerce in 2013.

"Our US trip is to materialize the essence of China-US sub-national cooperation and launch concrete cooperation in sectors of finance, trade, culture, technology, among others," he said.

San Francisco Mayor Ed Lee, who attended the Qingdao event, hailed the healthy bilateral relationship. "We two cities share many similarities, the hill and the ocean. We could promote innovation in the world by working together," he said.

The Sino-US economic relationship is the bedrock for a broader relationship between the world's two largest economies, said Luo Linquan, consul general in San Francisco. "Local and regional exchanges between the US and Chinese provinces, states and cities will help deepen mutual understanding and ultimately strengthen the China-US relationship as a whole."

Contact the writer at junechang@chinadailyusa.com