Let me tell you about my neighbor Sarah. She mailed wedding invitations last month and nearly had a disaster when half came back undelivered. Why? Comma confusion in the addresses. Turns out she'd written "Portland OR 97201" without the crucial city-state comma. Oops. That's when it hit me – where does the comma go in an address isn't just grammar nerds' territory. It's practical everyday stuff that affects whether your mail arrives, your packages get delivered, or your pizza shows up hot.
I've sorted mail at a university dorm, addressed thousands of business envelopes, and still see folks second-guessing comma placement. That little punctuation mark trips up smart people daily. We're going to fix that today with crystal-clear guidelines, real-life examples, and answers to every comma-in-address dilemma you've ever had.
The Core Rules: Where Commas Belong (And Where They Don't)
American address formatting follows specific comma logic. Here's the breakdown:
The Non-Negotiable City-State Comma
This is the golden rule: Always put a comma between city and state. No exceptions. Not sometimes. Always.
- Correct: Chicago, IL
- Correct: San Antonio, TX
- Wrong: Chicago IL (missing comma)
- Wrong: Chicago, IL, (extra comma)
Why does this matter? Postal scanners read "ChicagoIL" as one word. That comma is the separator telling machines where the city ends and state begins.
Honestly, I cringe when I see city and state jammed together online. It looks sloppy and creates actual delivery risks.
Apartment/Suite Numbers Demand Commas Too
When you've got secondary address elements – apartments, suites, units – they need commas before and after:
- Correct: 200 Central Park West, Apt 5B, New York, NY 10024
- Correct: 780 Mission St, Suite 400, San Francisco, CA 94103
Without commas? "200 Central Park West Apt 5B" could confuse sorting machines. Is "West Apt" part of the street name? Machines aren't that smart.
What About ZIP Codes? Comma or No Comma?
Here's where people overthink it. Never put a comma before or after the ZIP code. The state abbreviation flows directly into the ZIP:
- Correct: Boston, MA 02108
- Wrong: Boston, MA, 02108 (extra comma)
- Wrong: Boston, MA, 02108, (multiple errors)
Think of the ZIP code as attached to the state abbreviation. They're a package deal.
| Address Part | Correct Comma Usage | Wrong Examples | Why It Matters |
|---|---|---|---|
| Street address | No commas within street line | 123 North, Main Street | Commas should only separate distinct address components |
| Apartment number | Comma BEFORE apt/suite | 888 Broadway Apt 9F | Without comma, apt number blends into street name |
| City and state | Comma AFTER city | Seattle WA 98101 | Mandatory for USPS processing |
| State and ZIP | NO comma between state/ZIP | Austin, TX, 73301 | Extra comma creates processing errors |
Pro tip from my mailroom days: If you remember nothing else, drill this into your head – commas always go after the city name and before the state abbreviation. Get this right and you avoid 80% of addressing errors.
Special Situations: Where Comma Rules Get Tricky
Real life isn't textbook-perfect. Here's how comma rules adapt to complex addresses:
Business Complexes and Building Names
When addressing mail to specific buildings:
- Put building name on first line
- Street address on second line
- Building name and street address get commas between them if on same line
Same-line example: "Transamerica Pyramid, 505 Sansome Street, San Francisco, CA 94111"
International Addresses: Comma Differences
Canadian addresses follow similar rules but note: provinces get commas like US states:
- 100 Queen Street West, Toronto, ON M5H 2N1
UK addresses? They omit commas entirely between city and postal code:
- 10 Downing Street
London
SW1A 2AA
This inconsistency drives me nuts when ordering from overseas sites. Why can't everyone standardize?
Addresses Within Sentences
When an address appears mid-sentence, use commas around the entire address block:
"Our warehouse at 800 Jones Street, Oakland, CA 94607, will ship your order."
Forget this and your sentence becomes unreadable. Trust me, I've edited enough business documents to spot this error instantly.
| Situation | Comma Rule | Visual Example |
|---|---|---|
| PO Boxes | Comma after "PO Box" number | PO Box 874, Portland, ME 04101 |
| Rural Routes | Comma after route number | RR 5 Box 10, Lebanon, TN 37087 |
| Military Addresses (APO/FPO) | Comma after city equivalent | Unit 2050 Box 4190, APO, AE 09094 |
| Business Attn Lines | Comma after ATTN line | ATTN: Shipping Dept, 4400 West Florissant, St. Louis, MO 63108 |
Why Correct Commas Aren't Just Grammar Police Nonsense
Let's get real – why should you care? Three practical reasons:
1. Your Mail Actually Arrives
USPS processing centers use optical scanners that look for comma patterns. No city-state comma? Your letter might get routed to a dead letter office. I've seen it happen with college applications – heartbreaking when deadlines are missed because of a missing comma.
2. Professionalism Matters
An address full of comma errors makes you look careless. Job applications? Vendor contracts? First impressions stick. One hiring manager told me she rejects resumes with addressing errors immediately.
3. Digital Systems Parse Addresses
eCommerce forms, CRM databases, shipping platforms – they all rely on proper comma placement to auto-fill fields correctly. Ever had a website reject your "valid" address? Chances are comma errors were the culprit.
Confession time: I messed this up on my first mortgage application. Put "Philadelphia PA 19104" without the comma. The lender's system kicked it back as invalid. Cost me an extra day of processing during a tight closing window. Never again.
Address Format Showdown: One-Line vs Multi-Line
This trips people up constantly. Comma rules change based on how you format the address:
Single-Line Addresses (Forms, Databases)
Full comma rules apply:
- 123 Maple Ave, Unit 3, Denver, CO 80206
Every component separator needs a comma. No exceptions.
Multi-Line Addresses (Envelopes, Packages)
Line breaks replace most commas:
Maria Rodriguez 4400 West Florissant St. Louis, MO 63108
Notice:
- No comma after street address
- Comma ONLY between city and state
- No comma before ZIP
USPS specifically requests this format for automated processing. Deviate at your own risk.
| Format Type | Where Commas Appear | Where Commas Disappear | USPS Approval |
|---|---|---|---|
| Single-line | After street, after unit, after city | Never within street names | ✅ Accepted |
| Multi-line | Between city and state ONLY | End of address lines | ✅ Preferred |
| Hybrid formats | Inconsistent comma placement | Lines with internal commas | ❌ Causes errors |
Seriously, I wish more e-commerce sites understood this. Nothing worse than a checkout form that forces comma-heavy addresses onto multiple lines. Guaranteed shipping problems.
Top 5 Comma Mistakes I See Everywhere
After reviewing thousands of addresses, these errors appear most frequently:
- The City-State Smush: "MiamiFL 33101" – Scanners read this as one word
- Comma Happy Before ZIPs: "Atlanta, GA, 30308" – That extra comma is unnecessary noise
- Apartment Amnesia: "55 Main St Apt 4" – Missing comma before apt number
- Direction Confusion: "100 South, Main Street" – Commas don't belong within street lines
- International Projection: Applying US rules to foreign addresses like "Paris, France 75001" – French postal codes don't need commas
Your Comma Questions Answered (Finally!)
The exact phrase "where does the comma go in an address" comes up constantly. Let's resolve these once and for all:
Where does the comma go in an address with two street lines?
Never between street lines. Format as:
55 East 52nd Street Floor 17 New York, NY 10022
Where does the comma go in an address when the city has multiple words?
Still just one comma after the full city name:
- Correct: Oklahoma City, OK 73102
- Wrong: Oklahoma, City, OK 73102 (disastrous!)
Where does the comma go in an address for university mail?
Dorms follow standard rules:
Student Name 1400 Washington Ave, Room 205 Albany, NY 12222
Where does the comma go in an address with a business name?
Business name on separate line with no commas:
Tech Solutions Inc 3300 Enterprise Parkway Cleveland, OH 44122
Where does the comma go in an address if you're using "c/o"?
Comma after c/o line:
c/o James Wilson, 888 Commonwealth Ave Boston, MA 02215
Practical Drill: Fix These Addresses
Test your skills. Where should commas go?
- 1500 Market Street Philadelphia PA 19102
- 40 Fulton St Suite 12 New York NY 10038
- PO Box 7023 Madison WI 53707
Answers:
- 1500 Market Street, Philadelphia, PA 19102
- 40 Fulton St, Suite 12, New York, NY 10038
- PO Box 7023, Madison, WI 53707 (comma after PO Box number)
The Last Word on Address Commas
After all this, what's the absolute takeaway? That comma between city and state is non-negotiable. It's the backbone of proper addressing. Get that right and the rest falls into place. For apartment numbers and suite designations, remember they always get commas as bookends.
Next time you address an envelope or fill out a shipping form, pause for two seconds. Check that comma after the city. Your mail carrier will thank you, your packages will arrive faster, and you'll never face my neighbor Sarah's wedding invitation disaster. Honestly, I wish someone had explained this clearly to me years ago – would've saved so much returned mail and frustration.
Still unsure about where does the comma go in an address for your specific situation? Bookmark this page. I update it quarterly with new examples from reader questions.
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