Where should you add commas to the address make it grammatically correct after and ldquoBoston ldquoMassachusetts ldquo1000 an?

"Boston, Massachusetts, 1000"

Here's why:

* City and State: You always use a comma between the city and the state.

* State and Zip Code: You use a comma between the state and the zip code, even if you are writing out the full state name.