Street addresses in the United States are assigned by local government — typically the city’s planning, building, engineering, or GIS department for property inside city limits, and the county’s equivalent office (often the 911 coordinator) for unincorporated land. The question of who assigns street addresses has a consistent answer at the level of authority, even though the specific desk varies from one jurisdiction to the next. Federal agencies do not assign addresses. The U.S. Postal Service standardizes how addresses are written and decides where mail gets delivered, but it does not decide what number goes on your house.
Which Local Office to Contact
The office that handles addressing depends on where your property sits and how your local government is organized. Inside a city, it is usually the planning department, the building department, the engineering division, or a GIS office. In unincorporated county areas, responsibility often falls to the county planning department, a county GIS division, or the emergency management office. Many rural counties assign addresses through their 911 coordinator, because the push to implement Enhanced 911 forced those counties to replace route-and-box numbering with proper street addresses in the first place.
The authority behind all of this is a local ordinance. That ordinance sets the numbering grid, the naming conventions, and the process property owners follow to request an address. Some counties delegate the work to a regional council of governments or a joint-powers agency, but the underlying authority stays local. No federal law dictates how addresses must be assigned.
If you are not sure which office to call, start with the county or city clerk. They can point you to whichever department in your specific jurisdiction handles addressing.
How an Address Actually Gets Assigned
A new address is created when something changes on the ground: a house is built, a parcel is subdivided, a commercial building adds an entrance, or an accessory dwelling unit goes up in the backyard. The process usually begins when a property owner or developer submits an application to the local addressing authority, often as part of a building permit or a subdivision plat approval.
For a large development, addressing happens during the platting phase. The developer submits a plat showing the proposed lots and streets, and the addressing authority assigns numbers based on the jurisdiction’s grid. For a single new home, the address is usually assigned during building permit review. The addressing office will want a site plan showing where the structure sits on the lot and where the primary entrance or driveway meets the public road, because that access point determines the address number.
Once an address is assigned, the local authority notifies the relevant agencies: the postal service, the local 911 center, utility providers, and sometimes the county assessor. Processing times vary. Some jurisdictions turn around simple requests in a few days. Others take several weeks, especially when a site visit is needed or the situation is unusual, like a flag lot or a parcel with access from more than one street.
How to Request a New Address
If you need a new address for new construction, a property split, or an ADU, contact your city or county’s planning, building, or GIS department. Bring:
- The property’s parcel identification number and legal description
- A site plan showing the structure’s location and its access point to the public road
- Documentation of site control, such as a deed or purchase agreement
Some jurisdictions charge an administrative fee for address assignment. Fees vary widely by location, and some places bundle the cost into the building permit application rather than charging separately.
Vacant Land
A common question is whether you can get an address for raw, undeveloped land. In most jurisdictions the answer is no. Addresses are assigned to structures, and you typically need to apply for a building permit before an address will be issued. Some counties will assign a “location address” to vacant land for 911 purposes if there is a driveway or access point, but this is not universal. If you are buying land and need an address for utility hookups, call the county’s addressing office early.
Accessory Dwelling Units
Accessory dwelling units need their own unique addresses for mail and emergency response. A detached ADU with its own exterior entrance usually receives the main house’s street number with a letter appended, such as “123A Main Street.” An internal unit reached through a shared hallway typically gets a unit designation instead, such as “123 Main Street, Unit B.” Every new dwelling unit needs its own identifier, so check with the local addressing authority before applying for permits.
Corner Lots
A property at an intersection creates a judgment call about which street the address belongs to. Standard practice is to assign the address based on whichever street the front door or primary driveway faces. Jurisdictions handle split situations differently — where the front door faces one street and the driveway enters from another, results vary. Clarify this with your local authority before construction. Changing an address after the fact is far more work than getting it right the first time.
Correcting a Wrong Address
If your address is wrong — a number that does not fit the grid, a street name misspelled in the original assignment, or a secondary unit that was never properly designated — contact the local addressing authority, explain the discrepancy, and provide documentation. The correction process mirrors the assignment process. Once the change is official, you will need to update each downstream system yourself: USPS, 911, utilities, voter registration, property tax records, driver’s license, insurance.
Changing a street name is a bigger project. Most jurisdictions require a formal petition showing community support, often signed by a supermajority of affected property owners and tenants, along with a demonstrated reason the change benefits the neighborhood. A street name change affects every property on the street, so the bar is deliberately high. Expect public hearings, notice requirements that may include multiple languages, and a timeline measured in months.
Where the USPS Fits In
The Postal Service does not assign street addresses, but it has enormous influence over how they are formatted and used. Publication 28, the USPS addressing standards manual, defines the components of a delivery address line and prescribes the abbreviations and positioning for each. Local addressing authorities generally design their conventions to be compatible with USPS requirements.
For buildings with multiple units, the USPS requires specific secondary designators: APT for apartment, STE for suite, FL for floor, BLDG for building, RM for room, and UNIT for unit. The preferred placement is at the end of the delivery address line, not on a separate line. A pound sign (#) is discouraged and recommended only when the correct designator is unknown.
The USPS also maintains its own Address Management System, which contains every deliverable address the postal service recognizes. When your local government assigns a new address, USPS has to add it to this system before mail will be delivered there. This creates a gap. Your local government may have officially assigned your address weeks before USPS recognizes it. If you are waiting for mail at a newly assigned address, call your local post office to confirm the address has been entered. The USPS also offers a free ZIP Code Lookup on its website that returns the standardized version of any delivery address.
Where the Federal Government Fits In
The federal role is coordination, not assignment. The U.S. Department of Transportation maintains the National Address Database, which compiles address data contributed by state, local, and tribal governments into a single national dataset. The NAD does not create or assign addresses. It aggregates what local authorities have already established, using a schema aligned with the Federal Geographic Data Committee’s Address Data Content Standard so that an address record created in one jurisdiction can be understood by agencies in another.
Mailing Address vs. Physical Address
The physical address is the geographic location of your property, assigned by local government and tied to a point on a map. The mailing address is where you receive mail, which might be a PO Box, a commercial mailbox, or a different location entirely. In rural areas where postal carriers do not deliver to individual homes, a PO Box in the nearest town serves as the mailing address even though the property has a separate physical address for 911 and utility purposes.
The distinction matters on forms. Government agencies, banks, and insurance companies often ask for both. Using a PO Box where a physical address is required, or the reverse, can cause delays, rejected applications, or returned documents.
After You Get the Address, Verify It Propagated
An address that exists in one database but not in others causes real problems: missed mail, billing errors, blocked utility connections, complications in real estate transactions, and, most seriously, emergency response failures. If your address is not in the 911 database, dispatchers may send responders to the wrong location or be unable to locate you at all.
After a new address is assigned or an old one is corrected, confirm the update reached the systems that matter:
- USPS, so mail will be delivered
- The local 911 center, so responders can find you
- Voter registration, which in most jurisdictions requires a separate change-of-address filing with the election office
- Driver’s license, insurance policies, and any accounts tied to your physical location
- Utility providers and the county assessor
The work is tedious. Skipping it leaves you with an address that technically exists but does not function everywhere it needs to.