If you are in the US and mailing something to Vietnam, the important thing is that the last line contains “Vietnam” written in English along with the postal code. The other lines can be written as they would be written if mailed in Vietnam - meaning that it might be preferable to write them in Vietnamese.

In the U.S. we don't have clusters, wards, or provinces. We don't use districts in the address. We don't typically use the name of the apartments either. However, if you are sending a letter to a person at their business address, you would include the name of the business. Addresses are written : Mrs. Mary Smith 123 Main ST, APT 204 San Diego, CA 19122 Mary Smith ABC Company 123 Main ST, APT 204 San Diego, CA 19122-8456 You can write out the word "Street" (instead of ST) and "Apartment," (instead of APT) and the state, but the post office prefers that you abbreviate them. All 50 states have a two-letter abbreviation. In my example, CA is for California. Also, every address has a zip code (not an area code), which is 5 numbers or 9 numbers with a hyphen. For example, 19122 or 19122-8456. Many people don't use the hyphen in their personal letters, but businesses do. We don't include the country unless we are in another country and sending a letter to the U.S. If we live in the U.S. and are sending a letter to a location in the U.S., the country is left off-- we only use city, state, and zip code.

In the US it is Line 1: Persons name Address: # street name apt # Address 2: City, State, Area code, Country