Ship congestion outside the biggest U.S. gateway for Asian imports remained elevated with the wait to offload containers lengthening to eight days, adding costs and complications for companies trying to stay well-stocked in an accelerating economy.

A total of 28 container ships were anchored awaiting entry into the neighboring ports of Los Angeles and Long Beach, California, as of Sunday, compared with 26 a week earlier though still below a peak of 40 in early February, according to officials who monitor marine traffic in San Pedro Bay. Another 16 are scheduled to arrive over the next three days, with seven of those expected to drop anchor and join the queue.

The average wait for berth space climbed to 8 days, compared with 7.9 days a week earlier, according to the L.A. port. That’s about triple the average delay in November.

The backlog, which started to form in October, has been tough to clear because of shortages of both equipment and labor needed to handle an unrelenting wave of imports. March is typically one of the slowest months for inbound merchandise, but the influx of steel boxes this year show few signs of easing.