LOS ANGELES — With China accounting for about 55 percent of trade at the Port of Long Beach and roughly 40 percent of business at the neighboring Port of Los Angeles, stable relations between Washington and Beijing are not an abstract diplomatic concern for the two busiest container ports in the United States.

　　That deep trade linkage means shifts in US-China ties can quickly ripple through cargo flows, jobs, consumer supply chains and investment across Southern California, according to the heads of the two ports.

　　"Stable and constructive relations between the US and China are important to the global economy, to US consumers and businesses, and to the reliability of international supply chains," Noel Hacegaba, CEO of the Port of Long Beach, said.

　　The two ports, located side by side in San Pedro Bay, form the largest container gateway in the US and anchor a vast logistics network of dockworkers, truckers, warehouses, railroads, retailers and exporters.

　　China has been Long Beach's largest trading partner by cargo volume for decades and now accounts for about 55 percent of the port's imports and exports, Hacegaba said.

　　He described Long Beach as "a vital link in the Pacific trade corridor", connecting Chinese manufacturers and exporters with US consumers, businesses and distribution networks, while also serving as a gateway for California goods headed to China.

　　At the Port of Los Angeles, ties with China are similarly deep. Gene Seroka, the port's executive director, said China accounts for approximately 40 percent of its business, more than two and a half times that of its next largest trading partner.

　　"China remains a critically important trading partner for the Port of Los Angeles, and our long-standing relationships with Chinese ports have opened the door to cooperation that goes well beyond moving cargo," Seroka said.