It’s a legal requirement to carry your green card with you at all times. INA 264(e) has required this for as long as I’ve been in the US (which is since 2004).
To be more specific:
>> (e) Every alien, eighteen years of age and over, shall at all times carry with him and have in his personal possession any certificate of alien registration or alien registration receipt card issued to him pursuant to subsection (d). Any alien who fails to comply with the provisions of this subsection shall be guilty of a misdemeanor and shall upon conviction for each offense be fined not to exceed $100 or be imprisoned not more than thirty days, or both.
Where evidence of registration is an I94 or a green card or whatever.
I’m constantly surprised how many permanent residents don’t do this.
Many don't do this because they don't feel the need. I've spent about a decade in the US as a green card holder, and the only cases I ever been asked for it is either crossing the border or being hired. And I never heard about anyone being fined (let alone going to prison) for failure to carry the green card on them. Yes, the law says that, but I don't think anybody paid much attention to that, at least until now.
Are you user proberts?
Personally I don’t carry my GC, because I’m far more likely to lose it than for anyone to ever ask for it. And it’s kind of a nightmare to replace, takes awhile and you can’t travel.
To put it another way, the $100 fine is less expensive to me than the consequences of losing it.