There are a lot of rules with datelines, but since you will usually be writing from only one location, once you learn that dateline, you will know all you practically need to know.
U.S. locations
Canadian locations
International locations
U.S. and Canadian locations are treated differently from the rest of the world when it comes to dateline style. You won’t see “United States” or “Canada” in a dateline. You will see the names of states, provinces and territories.
US locations
These US cities stand alone: (Do not use the name of the state. Just use the city name.)
ATLANTA
BALTIMORE
BOSTON
CHICAGO
CINCINNATI
CLEVELAND
DALLAS
DENVER
DETROIT
HONOLULU
HOUSTON
INDIANAPOLIS
LAS VEGAS
LOS ANGELES
MIAMI
MILWAUKEE
MINNEAPOLIS
NEW ORLEANS
NEW YORK
OKLAHOMA CITY
PHILADELPHIA
PHOENIX
PITTSBURGH
ST. LOUIS
SALT LAKE CITY
SAN ANTONIO
SAN DIEGO
SAN FRANCISCO
SEATTLE
WASHINGTON
For U.S. cities that do not stand alone, not all states are abbreviated. Spell out Alaska, Hawaii, Idaho, Maine, Ohio, Texas and Utah. Abbreviate the others.
Ala. — for Alabama
Alaska — this state is not abbreviated in text
Ariz. — for Arizona
Ark. — for Arkansas
Calif. — for California
Colo. — for Colorado
Conn. — for Connecticut
Del. — for Delaware
Fla. — for Florida
Ga. — for Georgia
Hawaii — this state is not abbreviated in text
Idaho — this state is not abbreviated in text
Ill. — for Illinois
Ind. — for Indiana
Iowa — this state is not abbreviated in text
Kan. — for Kansas
Ky. — for Kentucky
La. — for Louisiana
Maine — this state is not abbreviated in text
Md. — for Maryland
Mass. — for Massachusetts
Mich — for Michigan
Minn. — for Minnesota
Miss. — for Mississippi
Mo. — for Missouri
Mont. — for Montana
Neb. — for Nebraska
Nev. — for Nevada
N.H. — for New Hampshire
N.J. — for New Jersey
N.M. — for New Mexico
N.Y. — for New York
N.C. — for North Carolina
N.D. — for North Dakota
Ohio — this state is not abbreviated in text
Okla. — for Oklahoma
Ore. — for Oregon
Pa. — for Pennsylvania
R.I. — for Rhode Island
S.C. — for South Carolina
S.D. — for South Dakota
Tenn. — for Tennessee
Texas — this state is not abbreviated in text
Utah — this state is not abbreviated in text
Vt. — for Vermont
Va. — for Virginia
Wash. — for Washington
W. Va. — for West Virginia
Wis. — for Wisconsin
Wyo. — for Wyoming
Also: District of Columbia (DC)
Canadian locations
Three Canadian cities stand alone: MONTREAL, QUEBEC CITY, and TORONTO. Otherwise, use the name of the city followed by the unabbreviated name of the province or territory.
International locations
These international cities stand alone: (Do not use the name of the country. Just use the city name.)
AMSTERDAM
BAGHDAD
BANGKOK
BEIJING
BEIRUT
BERLIN
BRUSSELS
CAIRO
DJIBOUTI
DUBLIN
GENEVA
GIBRALTAR
GUATEMALA CITY
HAVANA
HELSINKI
HONG KONG
ISLAMABAD
ISTANBUL
JERUSALEM
JOHANNESBURG
KUWAIT CITY
LONDON
LUXEMBOURG
MACAU
MADRID
MEXICO CITY
MILAN
MONACO
MOSCOW
MUNICH
NEW DELHI
PANAMA CITY
PARIS
PRAGUE
RIO DE JANEIRO
ROME
SAN MARINO
SAO PAULO
SHANGHAI
SINGAPORE
STOCKHOLM
SYDNEY
TOKYO
VATICAN CITY
VIENNA
ZURICH
Also, the United Nations headquarters in New York stands along as “UNITED NATIONS — .”
Otherwise, most cities around the world are written like “CITY, Country — .” Note, do not write “United Kingdom” — instead use England, Northern Ireland, Scotland or Wales.
For exception locations, such as island nations, see the guide.