Rules that do not vary by state
Federal carry rules
These bind everywhere, on top of whatever your state allows. Several are decided for you by the map. The rest are here because drawing them would mean inventing a boundary — postal property has no statutory radius the way a school zone does, and a circle round a post office would be a guess wearing the clothes of a fact.
School zones
18 U.S.C. § 922(q) — Gun-Free School Zones Act
Within 1,000 feet of any public, parochial or private K-12 school.
The federal bar is separate from your state's. The exemption that matters most is narrow and widely misread: it applies to a licence issued BY THE STATE IN WHICH THE SCHOOL SITS, and only where that state verifies the holder is qualified. A permit another state honours does not exempt you. The zone is measured from the property line, not the building, and it crosses streets, homes and shops.
on the mapMapped nationally from school locations at the statutory 1,000-foot radius.
Read the textPost offices and all postal property
your permit does not help39 CFR § 232.1(l)
Any postal property, including the parking lot.
"Notwithstanding the provisions of any other law, rule or regulation, no person while on postal property may carry firearms, other dangerous or deadly weapons, or explosives, either openly or concealed, or store the same on postal property, except for official purposes."
The parking lot is the trap. Leaving a firearm locked in your car while you collect a parcel is storing it on postal property, which the text prohibits in the same breath as carrying. A state permit is irrelevant: the rule begins by overriding every other law.
A contract postal unit inside a private shop is generally not postal property, but a standalone post office and its lot are.
unsettledA federal district court in Florida held § 232.1(l) unconstitutional as applied to one defendant carrying in a postal parking lot (United States v. Ayala, M.D. Fla. 2023). That decision binds nobody else, the government appealed, and the Postal Service continues to enforce the rule nationwide. Treat it as in force.
Read the textFederal facilities and federal court facilities
your permit does not help18 U.S.C. § 930
Any building or part of a building owned or leased by the federal government where federal employees regularly work.
Applies to leased space as much as owned, so a federal office on two floors of a private tower is a federal facility. A court facility is treated more strictly still.
There is an exception for a firearm carried "incident to hunting or other lawful purposes", which sounds broad and is not: courts have read it narrowly, and it does not cover carrying for self-defence into a federal building. Posting is required for the ordinary offence but not for the court-facility offence.
Read the textArmy Corps of Engineers land
36 CFR § 327.13
Corps-administered water resource development projects — lakes, dams, campgrounds.
Since 2023 the Corps permits possession consistent with state law at most projects, reversing a long-standing prohibition, but the change is not uniform and individual project rules still bind. Corps land is frequently adjacent to state parks with entirely different rules and the boundary is rarely marked.
on the mapMapped from Corps recreation-area boundaries.
Read the textNational parks and wildlife refuges
54 U.S.C. § 104906
The land itself follows state law; the buildings do not.
Since 2010 you may possess a firearm in a national park to the extent the law of THAT STATE allows — a park spanning a state line changes rules mid-trail. Federal buildings inside the park remain federal facilities under § 930, so visitor centres and ranger stations are off-limits even where the trail outside is not.
Read the textBusinesses open to the public
Wolford v. Lopez, 609 U. S. ___ (2026)
Private property open to the public, for licensed carry.
Decided 25 June 2026, six to three. Hawaii had reversed the default: carrying on private property open to the public was a crime UNLESS the owner had expressly authorised it. New York had a similar rule. The Court held that violates the Second and Fourteenth Amendments, so the default across the country is now that you may carry into a business unless its owner says otherwise.
Read what it does not do. The owner's right to exclude survives entirely — the Court said proprietors "can admit or exclude persons who are carrying guns for self-defense" either way. The objection was to a STATE reversing the default by criminal law, not to a shopkeeper saying no. It also concerns LICENSED carry, so it does not answer what happens to someone carrying permitlessly.
What it leaves entirely to the states is the consequence of ignoring a posted objection: in some states a compliant sign makes entry itself a firearm offence, in others it is only trespass once you refuse to leave. Treat every sign as binding.
Read the textTransporting through a state that bars you
18 U.S.C. § 926A
A journey between two places where you may lawfully possess the firearm.
Protects transport, not carry, and only on every condition at once: lawful possession at both ends, unloaded, and neither firearm nor ammunition readily accessible from the passenger compartment — in a locked container, and the glove compartment and centre console do not count.
It protects a journey rather than a stay, so stopping longer than the trip reasonably requires can take you outside it.
unsettledCourts have treated § 926A as a defence raised after an arrest rather than a bar to being arrested. Travellers have been held on state charges in exactly these circumstances and had to prove the section applied.
Read the textAirport sterile areas
your permit does not help49 U.S.C. § 46505; 49 CFR § 1540.111
Beyond the TSA screening checkpoint, and the checkpoint itself.
The prohibition begins at the checkpoint, so presenting a firearm to TSA is already the offence. Landside areas of an airport — ticketing, baggage claim, the parking garage — are governed by state and local law instead, which varies sharply and is where most airport arrests actually happen.
Checked firearms are lawful when declared, unloaded and in a locked hard case, but that is an airline procedure rather than a carry right, and the state you land in governs the moment you pick the case up.
Read the textTribal land
your permit does not helpTribal sovereignty; varies by nation
Land held in trust for a federally recognised tribe.
A tribe is a separate sovereign. Its firearm code is neither the state's nor the federal government's, tribal codes are frequently unpublished, and a state permit generally carries no weight. Reservation boundaries are checkerboarded with fee land in many places, so you can cross in and out repeatedly on one road without a sign.
on the mapBoundaries mapped; the codes themselves are reported as unsettled, never guessed.
Read the text
A rule marked “your permit does not help” overrides state law by its own terms. Postal property is the one people are caught by most often, and the parking lot is why: leaving a firearm in your car while you collect a parcel is storing it on postal property, which the regulation prohibits in the same sentence as carrying.