Small things that bring fines or arrests: jaywalking, open drinks, littering, the smoking age, fireworks, trespassing, children alone.
Many US laws are local, and some surprise newcomers. A small ticket is not a disaster, but an arrest can create problems for your visa or green card. Here are the common ones.
On the street
Jaywalking: crossing the street outside a crosswalk or against a red signal can bring a ticket in many places. Some states and cities have relaxed this. This differs by state.
Open alcohol: drinking from an open can or bottle in public is illegal in most places.
Littering: throwing trash, cigarette butts or gum on the ground can bring a fine.
Public urination: can bring a ticket and sometimes worse charges.
Smoking: you must be 21 to buy tobacco or vapes. Smoking is banned in many parks, beaches and near building doors.
Property
Trespassing: entering private land or buildings without permission, even to take a photo or a shortcut, is illegal. Signs saying "No Trespassing" or "Private Property" mean stay out.
Taking items left on the street is usually fine only if they are clearly given away ("Free" sign). Taking things from a store's dumpster or someone's yard can be theft.
Fireworks and fire
Fireworks rules differ by state and city. In many places, most fireworks are illegal for the public. Check before buying, and never bring them on a plane.
Many areas ban outdoor fires and grills on dry days. Apartment balconies often have grill rules.
Children
Leaving children alone: there is no single federal age. Some states set a minimum age; others judge each case. Leaving young children alone at home or in a car can lead to a child neglect investigation. This differs by state.
Never leave a child in a car, even for a few minutes. Cars get dangerously hot fast.
Physical punishment: hitting a child in a way that leaves marks can lead to a report to child protective services.
Car seats are required for young children in all states.
Animals and nature
Dogs must be on a leash in most public places. Clean up after them.
Fishing and hunting need a state license.
Picking plants or taking rocks in national parks is not allowed.
Paperwork habits
Pay tickets on time or contest them by the deadline. Ignoring a ticket can lead to a warrant.
Keep every court paper. Later immigration forms may ask about any arrest, citation or charge.
Common mistakes
Thinking a ticket "does not matter" because you are a foreigner. Unpaid tickets can grow into bigger problems.
Following a custom from home that is illegal here, like letting a young child walk alone to a store in a busy city.