When addresses and place names appear in text, use commas to separate the individual elements. Think of it this way: at any point where you would start a new line when addressing an envelope, use a comma (so don’t set off abbreviations such as NE or zip codes with commas):
When touring the nation’s capital, make sure to schedule a visit to the White House, located at 1600 Pennsylvania Avenue NW, Washington, DC 20500, preferably in early April when the Japanese Cherry Blossoms are blooming.
When Jeff and I vacationed in Washington a few years ago, we rented a car and drove to Baltimore, Maryland, to watch the Vikings play the Ravens.
It can get awkward when you’re using a place name that requires a comma as an adjective:
This weekend, the Vikings played the Baltimore, Maryland, Ravens and beat them in a close game.
Your best bet is to rewrite the sentence to avoid the issue:
This weekend, the Vikings played the Baltimore Ravens and beat them in a close game.
This weekend, the Vikings played the Ravens from Baltimore, Maryland, and beat them in a close game.
Do you have a question about the comma? Let me know, and I’ll include it in a future installment of Mots Justes’ ongoing series.
The Mots Justes Series on Commas
Part I—To Serialize or Not to Serialize
Part X—Adjectival Phrases and Appositives
Part XII—Making the Transition
Resources
Chicago Manual of Style, The. 15th ed. Chicago: The University of Chicago Press, 2003.
Hacker, Diana, The Bedford Handbook for Writers, 3rd ed. Boston: St. Martin’s Press: 1991.
Mots Justes 