An address is such a simple piece of information, but you should take formatting an address very seriously. Commas help to distinguish the parts of an address, such as the building or house number, street, city, state and postcode. If writers made liberal use of commas, the reader might not get a clear and accurate understanding of the location. Those people who are driving to a destination need to know to where they are going. You can make sure you don't confuse readers by using a few editorial style guidelines when formatting an address.
Place a comma and space after the person's or place's name: "Anywhere City Hall, ."
Add a comma and space after the street address: "123 Main St., ." Add a comma after the department or apartment number: "123 Main St., Front Desk, ."
Set a comma and space after the city: "Anywhere City, ."
Put a space after the state, but do not include a comma. Also, add the zip code after the space: "Anywhere City, New York 10001."
Add a comma after the zip code if it is a part of a sentence: "Mail your correspondence to Anywhere City Hall, 123 Main St., Front Desk, Anywhere City, New York 10001, to ensure your concerns reach the mayor's office."
- You do not need to use commas when you address an envelope in the standard delivery address format, usually using three separate lines. However, do use a comma between the city and state.