The 20th anniversary of Hong Kong's return to China was celebrated by over 10,000 Chinese-Americans in New York and San Francisco over the weekend.

Zhang Qiyue, China's consul general in New York, said at a ceremony in Foley Square next to Chinatown on Sunday that the implementation of the one country, two systems principle has been "very successful".

She spoke highly of Hong Kong's stability and economic development since China resumed sovereignty over the territory on July 1, 1997.

"The Chinese community in the eastern USA will always support and care for our Hong Kong compatriots," Zhang said.

Many waved China's national flag and the regional flag of the Hong Kong Special Administrative Region at the celebration.

"We American Chinese in NYC rallied exactly here on July 1, 1997, when China resumed exercise of sovereignty over Hong Kong. The parade (before the rally) lasted several kilometers. It's such a touching moment that all of us will never forget," said Liang Guanjun, head of the US East Coast Chinese Association Federation.

On Friday in San Francisco, about 400 people from local businesses and political and academic communities in the Bay Area gathered to celebrate the anniversary.

"Twenty years ago, Hong Kong proudly reunited with our homeland. Under the one country, two systems arrangement, we are part of China but are able to maintain a unique identity," Clement Leung, Hong Kong commissioner for economic and trade affairs, USA, told guests at a celebratory gala reception hosted by the Hong Kong Economic and Trade Office in San Francisco.

During the past two decades, Hong Kong continued to be a premier international business center in Asia, with its economy nearly doubling in size, Leung said.

"We are the undefeated champion as the freest economy of the world for 23 years. We are the No 1 IPO stock market," he said.

Besides the pillar economic sectors of trade, financial services, tourism and professional services, new sectors and opportunities have emerged in Hong Kong.

Those include the development of RMB business, the implementation of the Stock Connect programs that enable international investors to access the Shanghai and Shenzhen stock markets, the vibrant innovation and technology startup ecosystem, wine auction and distribution, arts, culture and creative industries, as well as the Belt and Road Initiative, according to Leung.

Rui Nan in New York and Xinhua contributed to this story.

liazhu@chinadailyusa.com