Data & methodology

Every number on this site comes from an identified source with a stated cadence.

Sources

WSDOT Traveler API (official). Live sailing space, terminal directory, and schedules come from Washington State Ferries' public developer API, accessed with a registered key and an identified user agent. Attribution: Data source — WSDOT Traveler API. WSDOT updates sailing space as often as every 5 seconds; we deliberately check once a minute — fast enough to stay live, far below the feed's ceiling — and every number carries the freshness stamp you see on the board.

Published opening dates. Reservation-opening reminders are built from dates operators announce publicly. No scraping is involved.

Field definitions (drive-up, reservable, dashes, capacity) are described on the how it works page.

Known limitations

Live space reflects the operator's terminal systems and can shift between our check and your arrival. Counts shown as "—" mean the operator isn't displaying that space type for the sailing, which is different from zero. Sailing history begins the day our archive started; charts state their observation window.

Contact

Questions about the data — including from operators — reach a monitored inbox: hello@ferrysignal.com.