China's Guangdong province and Massachusetts celebrated the 35th anniversary of their sister relationship with a pledge for an even closer partnership.

In Boston on Friday, the two sides expressed their willingness to expand cooperation in innovation, promote two-way investment and widen people-to-people exchanges at the subnational levels despite the trade dispute between Washington and Beijing.

"For Guangdong and Massachusetts, we made our special friendship official in 1983," Massachusetts Lieutenant Governor Karyn Polito said in a speech at the ceremony. "Our administration will continue to work with Guangdong to expand cooperation in life sciences, robotics, clean energy and high-tech sectors."

Polito stressed the strong business dealings between the commonwealth and the province.

"We are pleased in Massachusetts to have your companies like the China Railroad Rolling Stock Corp (CRRC) building our train cars at this moment (and) others like Qilu Pharmaceuticals, WuXi AppTec and the Shanghai (Zhangjiang Boston) Enterprise Park," she said. "These are only a few examples, and we hope there are more to come in the future."

Guangdong Vice-Governor Ouyang Weimin represented the province at the gathering.

"The relationship between Guangdong and Massachusetts is one of the earliest established relationships between China and the US at the state level since China's reform and opening-up 40 years ago," Ouyang said. "The cooperation between our two states has brought tangible benefits to our two peoples."

Ouyang said that Guangdong has learned much from Massachusetts in the past 35 years through trade, technology, science education and culture.

"To further strengthen our cooperation, we should further expand our bilateral investment," said Ouyang. "Compared to our trade volume, the number of investments between Guangdong and Massachusetts is still relatively small.

"Secondly, we should also deepen practical cooperation in technology, innovation and education, and promote exchanges between higher education institutions and research and development institutions between our two states," Ouyang said. "Last but not the least, we should build a long-term communication and cooperation mechanism at the state-to-state level to realize a truly win-win cooperation."

Ouyang said he hopes the recent trade conflict between the two governments could be solved by mutual understanding and negotiation. "The trade protectionism is bad for consumers of both nations," he added.

Ouyang said that since China's reform and opening-up, Guangdong has changed dramatically, and President Xi Jinping mentioned at the Boao Forum in Hainan recently that China will open even wider.

"He specifically said it will broaden market access and create a more attractive investment environment to further strengthen the protection of intellectual property rights and expand imports," Ouyang said. "It will be a very good opportunity for us to promote our cooperation with businesses in Massachusetts."

Zhang Qiyue, the consul general of China in New York, whose consulate region includes Boston, said that "subnational cooperation has always been the cornerstone of the US-China relationship. Today, there are 49 pairs of sister states and more than 200 pairs of sister cities between China and the US".

"Over the last 35 years, Guangdong and Massachusetts have engaged in fruitful cooperation in many sectors, including trade, investment, science and technology, innovation, culture and people-to-people exchanges and delivered tangible benefits to both peoples," she said.

Zhang said that "it's precisely because of this subnational cooperation and people-to-people exchanges, that China-US relations enjoy robust growth, and friendship really overwhelms in China-US relations".