For fellow Americans living in cities where ICE is active, many people, especially those of Hispanic descent, are already carrying around passports on their persons at all times because they're rightfully afraid of being forcibly disappeared or deported to some random South American country.
A passport card can be obtained for $30 from the Department of State. It is considered exactly equivalent to a passport within the US, but it's the size of a credit card. It is a valid travel document for land and sea travel within North America and the Caribbean. It also counts as a Real ID. The card is good for ten years.
Do not do this if you are transgender or have an X gender marker. They will cancel your passport and tell you to apply for a new one with your sex assigned at birth.
This is actually not super common. I was personally stopped by them and I was let go after showing my passport card. Ideally, ICE should not be arresting any citizens, but it happens anyway because they'll hire anyone who can breathe and do a decent seig heil. Nonetheless, a thing that works 80% of the time is still worth having.
Edit: I have managed to create a statistic for this. There are 22,000 agents which work for ICE, although this number was 12,000 prior to Trump's hiring surge (source). ICE claims they made 26,600 arrests in 2025 (source). This means each agent makes about 2 arrests per year on average at most. So unless you believe that most agents are checking only three or four people a year, this would indicate most people are being let go.