Port activity on the East and West Coasts remained strong heading into the fall, but some officials say the uncertain global trade outlook puts a question mark on the longer term outlook.

Officials at the Port of New York and New Jersey reported another record-breaking month this week, citing a 4.3% year-over-year increase in overall cargo volume in August, the most recent monthly data reported. The port moved 679,585 twenty-foot-equivalent units (TEUs) during the month, bringing year-to-date volume to more than 4.9 million TEUs, officials said. Import loads increased 2.7% during the month while export loads rose 1.7%, officials added.

On the West Coast, officials at the Port of Oakland said loaded container volume rose 3.1% year-to-date in September, with loaded imports up 3.5% and loaded exports up 2.7%. Officials cited continued demand for imports to the strong Northern California economy as key to the growth, adding that export volumes continue to grow as U.S. shippers seek new markets outside of China.

Oakland's overall container volume was up just 1.3% in the first nine months of the year, however, due to lower volumes of empty containers being repositioned from the U.S. back to Asia. Ocean carriers are moving less empty containers because Oakland's imports and exports are returning to a 50/50 balance after last year's surge of loaded imports, officials said.

"We're encouraged that our loaded containers are showing strong growth," Port of Oakland Maritime Director John Driscoll said in a statement announcing the results earlier this month. "We remain cautious but optimistic that we can maintain this cargo volume performance through the rest of the year."

Officials at the Port of Los Angeles were less optimistic. Despite a 4.7% increase in total cargo volume for the first nine months of the year, officials cited a 2.7% decline in September volume, when the port moved 779,903 TEUs. September imports fell 2.9% and exports decreased 11%, the 11th straight monthly decline of exports.

"The ill-advised U.S.-China trade war continues to wreak havoc on American exporters and manufacturers," Port of Los Angeles Executive Director Gene Seroka said in an October 10 statement. "We've seen declining exports for 11 consecutive months while our fastest growing market segment is exporting empty containers back to Asia. It's likely we'll see softer volumes in the fourth quarter. We must have a negotiated settlement of the trade war, as it is beginning to impact the more than 3 million jobs in the U.S. that are tied to this port complex."

Trade talks continue between U.S. and Chinese officials following an October 11 announcement of a partial trade deal between the two countries. At that time, President Trump suspended additional tariffs on Chinese imports that were set to take effect this month. Discussions may continue next month, when President Trump and Chinese President Xi Jinping are both set to attend a November 16 summit of the Asia Pacific Economic Cooperation countries in Santiago, Chile.