The Port of Long Beach saw its busiest October in four years, due mainly to a seasonal rise in imports.

More than 583,000 containers passed through the port last month, typically the final month in the peak August-through-October season, the Harbor Department reported late Monday.

That volume, however, was just 1.1 percent greater than the year-ago period. That could be due to some shipments being pushed into November in reaction to congestion-related delays at both ports, port officials said in announcing the numbers.

Traffic is up 1.7 percent overall through the first 10 months of the year.

While October imports grew 4.1 percent compared to a year ago, exports dropped 14.9 percent. A rise in imports is common during the holiday season, according to port officials.

In comparison, the Port of Los Angeles saw cargo volume rise 4.6 percent in October compared to a year ago, the Harbor Commission said Monday.