I like maps and recently learnt the U.S. state abbreviations by heart for no particular reason. The abbreviations are highly irregular, both for logical reasons and historical reasons, which makes them especially hard to learn. I created a set of rules that may help you remember the abbreviations more easily. The rules are very straightforward, as my goal was to avoid creating rules that have multiple levels of exceptions.

There are eight rules divided into three categories. Firstly, states that consist of two words have one very simple rule. Secondly, states that start with M, A, I, or N have a complicated rule each. Finally, the remaining states have a very simple rule depending on the first letter.

1. Two-word states
   If the state consists of two words, the abbreviation is the first letter of each word.

   State	Abbreviation
   New Hampshire	NH
   New Jersey	NJ
   New Mexico	NM
   New York	NY
   North Carolina	NC
   North Dakota	ND
   Rhode Island	RI
   South Carolina	SC
   South Dakota	SD
   West Virginia	WV
   District of Columbia	DC
   Puerto Rico	PR

2. MAIN states
   The following four rules describe states that start with M, A, I, or N. These are the most frequent first letters, and are the most complicated to remember.

   1. M states
      These are by far the hardest to remember, because there is no real structure to them. But we can sub-divide this into three categories: starting with MA, starting with MI, and starting with MO. Once you figure that out, you can use mnemonics to distinguish them from each other.

      State	Abbreviation	Mnemonic
      Maine	ME	All other options are taken
      Maryland	MD	Medical Doctors live in Maryland
      Massachusetts	MA	Easternmost MA state gets simplest abbreviation
      Michigan	MI	Easternmost MI state gets simplest abbreviation
      Minnesota	MN	All other options are taken
      Mississippi	MS	Many S's
      Missouri	MO	Miss Ouri
      Montana	MT	MounTain

   2. A states
      We actually have two sets of two here: two states starting with AL, and two starting with AR. I've come up with a few mnemonics to help you distinguish them.

      State	Abbreviation	Mnemonic
      Alabama	AL	Al lives in Alabama
      Alaska	AK	Alaskans like Kalashnikovs?
      Arizona	AZ	Z is unique, so use it when you can!
      Arkansas	AR	Pirate says "Arr"

   3. I states
      Use the first two letters, unless it's Iowa. As a mnemonic, try "I owes an A".

      State	Abbreviation
      Idaho	ID
      Illinois	IL
      Indiana	IN
      Iowa	IA

   4. N states
      This one requires a bit of deduction. Both Nebraska and Nevada could use NE, but if we give NE to Nevada then Nebraska becomes NB, and no abbreviation ever uses the letter B. Therefore, we must give NE to Nebraska.

      State	Abbreviation
      Nebraska	NE
      Nevada	NV

3. Simple rules
   All remaining states are very regular, and we can determine the abbreviation by looking at the first letter.

   1. Texassee
      If we're talking about Tennessee or Texas, the abbreviation is the first and third letter.

      State	Abbreviation
      Tennessee	TN
      Texas	TX

   2. WOODRUFF states
      If the name starts with a letter of WOODRUFF, the abbreviation is the first two letters.
      Remember that Rhode Island is already covered by the very first rule!

      State	Abbreviation
      Delaware	DE
      Florida	FL
      Ohio	OH
      Oklahoma	OK
      Oregon	OR
      Utah	UT
      Washington	WA
      Wisconsin	WI
      Wyoming	WY

   3. HYPERCLEVER GEEK states
      If the name starts with a letter of HYPERCLEVER GEEK, the abbreviation is the first and last letter.
      Alternatively, remember that these are the states that start with a consonant, but are not covered by MAIN, WOODRUFF, or Texassee. Either way, remember that Rhode Island is already covered by the very first rule.

      State	Abbreviation
      California	CA
      Colorado	CO
      Connecticut	CT
      Georgia	GA
      Hawaii	HI
      Kansas	KS
      Kentucky	KY
      Louisiana	LA
      Pennsylvania	PA
      Vermont	VT
      Virginia	VA

And that wraps up the list of rules! Good luck with learning!