A rural mailbox must sit 41 to 45 inches above the road surface, measured from the road to the bottom of the box or the point where mail enters, not to the top of the box or the post.1United States Postal Service. How to Install a Mailbox The front face of the box also has to sit 6 to 8 inches back from the curb or road edge.2United States Postal Service. City Motorized, Rural, and Contract Delivery Service Routes Miss either range and USPS can suspend delivery until you correct it.
Measuring the Height Correctly
The reference points matter more than the tape measure. Measure from the road surface directly beneath the box up to the bottom of the box, or to the slot where mail is inserted if that sits lower.1United States Postal Service. How to Install a Mailbox Do not measure from the driveway, the sidewalk, or the grass at the base of the post. Those surfaces can differ from the road by several inches, and a box that looks right against the driveway can still fail because the carrier reaches from a vehicle sitting on the pavement.
The range exists because carriers deliver from inside their trucks. Too high and they cannot reach the box comfortably; too low and they have to stoop. Either problem slows down every stop on the route, which is why USPS treats the numbers as a hard requirement rather than a suggestion.
Setback From the Road
The face of the box needs to be 6 to 8 inches back from the curb or road edge.2United States Postal Service. City Motorized, Rural, and Contract Delivery Service Routes That distance keeps the box in reach of the carrier’s window while giving it some protection from passing traffic and snowplows. If there is no raised curb, contact your local post office for guidance on where to measure from, since unpaved shoulders can shift and quietly change the setback over time.1United States Postal Service. How to Install a Mailbox
Post Depth and Material
Height only counts if the post underneath is set up correctly. The Federal Highway Administration recommends a 4-inch by 4-inch wooden post or a 2-inch-diameter standard steel or aluminum pipe.1United States Postal Service. How to Install a Mailbox Both are strong enough to hold the box upright and weak enough to give way if a vehicle hits them.
Bury the post no more than 24 inches deep.3United States Postal Service. Mailbox Improvement Week, May 21-27 Going deeper, filling the hole with concrete, or encasing the post in a stone pillar defeats the breakaway function and can result in suspended delivery. A concrete-anchored post also becomes a serious injury risk to any driver who strikes it.
The Box Itself
Any mailbox you install should carry the Postmaster General’s seal of approval, which confirms it meets USPS size and construction standards.1United States Postal Service. How to Install a Mailbox Most boxes sold at hardware stores already have this seal. The box cannot be made from transparent, toxic, or flammable material, and it cannot carry advertising on the box or the support. Locks or inserts that shrink the interior opening or force the carrier to use a key are not allowed, and there is no local postmaster exception for the lock prohibition.4United States Postal Service. USPS STD 7C01 – Mailboxes, Curbside All new installations and replacements must use an approved model.5United States Postal Service. Postal Operations Manual – Section 632
Signal Flag
A working carrier signal flag makes your box “full service”; without one it’s “limited service.”4United States Postal Service. USPS STD 7C01 – Mailboxes, Curbside The flag can be almost any color except green, brown, white, yellow, or blue. Fluorescent orange is preferred, and it must contrast clearly with the box.6United States Postal Service. USPS Standard Mailboxes, Curbside Mount it where the carrier can raise and lower it from the vehicle.
House Number
Your house or box number must appear on the mailbox in contrasting-color letters and numerals at least one inch tall.2United States Postal Service. City Motorized, Rural, and Contract Delivery Service Routes Put the number on the side of a standalone box, or on the door if yours is part of a group installation. If the mailbox sits on a different street than your house, add the full street address so the carrier can match it to the right route.
Keeping the Approach Clear
A correctly installed box still has to be reachable. You are responsible for keeping the approach clear so the carrier can pull up, stop, and drive away without backing up or getting out.7United States Postal Service. Postal Service Seeks Help Keeping Access to Mailboxes Clear of Snow In winter, that means clearing snow around the base and along the truck’s path. Overgrown shrubs, parked cars, and trash cans block access just as effectively. If the carrier cannot safely reach the box, delivery stops until the obstruction is gone.
What Goes in the Box
Federal law reserves your mailbox for postage-paid U.S. Mail delivered by authorized postal carriers. Flyers, business cards, and menus placed by anyone else are not permitted. Newspapers are the narrow exception on Sundays, when postal delivery does not run; a separate newspaper tube can be mounted on the same post if you prefer to keep publications out of the box entirely.
Once the box is up, federal law also protects it. Deliberately damaging, tearing down, or destroying a mailbox, or breaking one open, is a federal crime punishable by a fine, up to three years in prison, or both.8Office of the Law Revision Counsel. United States Code Title 18 Part 1 Chapter 83 – Postal Service Report vandalism to your local postmaster and to the U.S. Postal Inspection Service.