The two adjacent ports are reporting a decline of 43 per cent in overstaying containers, compared to a 46 per cent reduction the week before and 47 per cent the week before that. "Progress has eased due to year-end holidays," the Port of Long Beach said in a statement.

The executive directors of both ports will reassess the fee's implementation after monitoring data over the next week, pushing implementation to no earlier than January 3.

The ports plan to charge ocean carriers in these two categories US$100 per container, increasing in $100 increments per container per day until the container leaves the terminal.