Dwell, explained precisely: vessel dwell vs box dwell vs ships waiting

Container dwell time means three different things at a port, and treating them as one number is how readers reach the wrong conclusion. Vessel dwell is how long a ship sits at a berth. Box dwell is how long an import container sits on the terminal after it comes off the ship. Ships waiting is a count of vessels queued offshore before they ever reach a berth. Same word, three clocks, each measured from a different point by a different source.

Vessel dwell: the ship at the berth

Vessel dwell at berth is the time a container ship spends tied up working cargo, from arrival at the berth to departure. The Bureau of Transportation Statistics built this one from Coast Guard vessel-position signals, the AIS transponders every ship broadcasts, and published a national average in hours for the largest US container ports. It is a ship metric, a read on how long the loading and discharge took. BTS ran the series from 2019 through June 2023 and then stopped, so every vessel-dwell figure on this site is an archived historical number, clearly labeled, never a reading for this week.

Box dwell: the container on the terminal

Box dwell, sometimes called container dwell, is the clock the trade actually means when it says dwell. It counts how long an import container sits in the terminal yard after discharge before it leaves by truck or rail. That is the number that drives free-time exposure, because a box sitting past its free days starts running up storage charges. The Pacific Merchant Shipping Association publishes it monthly for Los Angeles and Long Beach, split into truck-bound and rail-bound cargo, on roughly a two-month lag. There is no single free national feed for box dwell, so this site does not carry a box-dwell series of its own and points to PMSA for the LA/Long Beach figure.

Ships waiting: not a dwell at all

Ships awaiting berth is a headcount, not a duration. It is the number of container ships sitting at anchor or slow-steaming offshore because no berth is open yet. The Marine Exchange of Southern California has counted the San Pedro Bay queue since October 2020, and MARAD compiles the national picture that feeds the public table. It is the most current congestion signal on this site, updated weekly, which is why the homepage board leads with it. A long queue means ships are stacking up before the dock. It says nothing on its own about how long a box will then sit on the terminal.

Reading the two live modules together

The archived chart above is vessel dwell, hours a ship sat at a US berth, and it stops in mid-2023. Read it as history, a record of how long ships worked cargo during and after the pandemic crunch, not a live gauge.

The chart above is the live one, the count of ships waiting off LA/Long Beach this week. It tells you whether vessels are backing up offshore right now. Neither number is box dwell, and neither tells you what a specific container will do on the terminal. Keep the three apart and each answers a clean question. Blur them and you will read a two-year-old ship average as today's cargo delay.

The Dwell labels every dwell number with its exact clock and its source. It does not forecast congestion and it is not routing or fee advice. For how these clocks line up along the import chain, see from ship to your warehouse.