Washington DC is commonly called DC, Kuala Lumpur is KL. What other cities have popular two or three letter names?
Beijing is commonly referred to in China as “BJ”
DFW seems to be in pretty wide use.
(Dallas-Fort Worth, Texas for our non-US members)
“LA” is the metropolis of Lewiston-Auburn, Maine.
It’s common to see New York referred to as NYC in writing, but I don’t think I’ve ever heard it referred to that way.
Atlanta is known as ATL to some.
Sacramento = Sac (pronounced “sack”)
Orange County = OC
I’m originally from KC (as in KC Masterpiece).
Chicago = Chi-Town, but that’s not really any shorter. Personally I like CBS (City of the Big Shoulders) or HBW (Hog Butcher to the World). Then there’s OAR (O’Hare airport).
How about 4 letters? The area around Fort Rucker was known as UCLA when I was there.
Ugliest Corner of Lower Alabama
I thought O’Hare is ORD? 
You’re right, my mistake. 
Bangkok = BKK
Ho Chi Minh city = HCM City
Hong Kong = HK
Pittsburgh is PGH
St. Louis - STL
I refer to Minneapolis as MSP.
Toronto is affectionately known as TO.
…or, if you’re trying to be all ghetto n’ stuff, as the T-Dot.
I live in the “D”.
Which makes things confusing when the media refers to Terrell Owens as “T.O.” Toronto was known as “T.O.” before Owens was even born.
New Orleans - NOLA
Atlantic City - AC