This collection includes border crossings from Canada to the USA, passenger manifestoes, seafarer records and a lot more.
If you don't already have an Ancestry account, you will need to register for a guest account. You only need to give name and email address for one of these; Ancestry then emails you a password and username. There's no signing up for a subscription, no giving your credit card details and no need to cancel anything after the free access ends.
The free access expires on Monday 7th September 23:59 ET (Tuesday 8th September 04:59 UK).