If a cell value equals this, another cell equals that - excel

Question

I have a spreadsheet with a column for cities, of which their are only 4 different values. What is the formula for equating a new column to show the corresponding state and apply it to the entire list? Example:
Atlanta equals GA,
Phoenix equals AZ,
Chicago equals IL,
Nashville equals TN
Thanks!!

Answer 1

You can use the VLookup function for that:
Make a table with your city name in one column and the state in the next column. Then the following formula next to the city that you want populated:
=VLOOKUP(A1,A$20:B$23,2,FALSE)
In this example, the city you want to identify is in A1, and this formula goes in B1. You can copy it down to B2, B3, etc because the table is hard-coded as A$20:B$23, rather than A20:B23 (where each successive copy down the column would look for a table one row down as well). This example put the lookup table in the A-B columns, but you could put it anywhere you like.
The FALSE at the end means, look for an exact match, not closest. So if you get a "Dallas" in your list, the function will return NA rather than guessing between the state for Chicago and the state for Nashville (either side of Dallas, alphabetically).
Hope that helps!
EDIT:
You added that you also need zipcode info, and that's easy enough to add.
Your table that defines everything would put the zipcode in the 3rd column, so down at A20:B23 (in my example above) you'd end up with A20:C23, where the table would look like
Atlanta GA 12345
Chicago IL 23456
Nashville TN 34567
Phoenix AZ 45678
The cell next to your city in the table you want to populate would be in B1 as shown above giving the state, and then in C1 you'd have the following formula:
=VLOOKUP(A1,A$20:C$23,3,FALSE)
The changes are that here the table is defined out to column C, and instead of "2" returning the second column (i.e. the state abbreviation shown in B), it returns the zipcode shown in column C, the third column.
Again, hope that helps.

Answer 2

Since you mention "only 4 different values" maybe:
=CHOOSE(MATCH(LEFT(A1),{"A","P","C","N"},0),"GA","AZ","IL","TN")

Answer 3

You can use a VLOOKUP Table that contains the city and state abbreviation.
Here is a table that has the Capital, State, State Abbreviation.
Montgomery Alabama AL
Juneau Alaska AK
Phoenix Arizona AZ
Little Rock Arkansas AR
Sacramento California CA
Denver Colorado CO
Hartford Connecticut CT
Dover Delaware DE
Tallahassee Florida FL
Atlanta Georgia GA
Honolulu Hawaii HI
Boise Idaho ID
Springfield Illinois IL
Indianapolis Indiana IN
Des Moines Iowa IA
Topeka Kansas KS
Frankfort Kentucky KY
Baton Rouge Louisiana LA
Augusta Maine ME
Annapolis Maryland MD
Boston Massachusetts MA
Lansing Michigan MI
Saint Paul Minnesota MN
Jackson Mississippi MS
Jefferson City Missouri MO
Helena Montana MT
Lincoln Nebraska NE
Carson City Nevada NV
Concord New Hampshire NH
Trenton New Jersey NJ
Santa Fe New Mexico NM
Albany New York NY
Raleigh North Carolina NC
Bismarck North Dakota ND
Columbus Ohio OH
Oklahoma City Oklahoma OK
Salem Oregon OR
Harrisburg Pennsylvania PA
Providence Rhode Island RI
Columbia South Carolina SC
Pierre South Dakota SD
Nashville Tennessee TN
Austin Texas TX
Salt Lake City Utah UT
Montpelier Vermont VT
Richmond Virginia VA
Olympia Washington WA
Charleston West Virginia WV
Madison Wisconsin WI
Cheyenne Wyoming WY
Then you would use =VLOOKUP(A1,A1:C50,3, FALSE) to look for A1 (Montgomery) in the table and it would output AL for example.