I'm doubting that we'll ever get an answer (at least not any time soon) unless we collaborate on this one, so I figured it'd be good if someone set up a wiki post for everyone to contribute to. I've made the references that have already been cracked bold to make it easier to distinguish them from all the others.
If you have any ideas or actual answers, then feel free to update this post with whatever you've got!
First in freeways - 2H77JE
Possibly on hit on North Carolina's "First in Flight" license plate slogan. Well: "North Carolina has the second largest state maintained highway network in the United States[...]", but: "North Carolina Is The Good Road State" (https://www.ourstate.com/good-road-state/).
The 'yuh-huh' state - 7BMA12
Have an idea of what "The 'yuh-huh' state" may refer to?
Jewel of the fracking belt - DX156A
Have an idea of what "Jewel of the fracking belt" may refer to?
Still a British colony at heart - 1FGFI3
Have an idea of what "Still a British colony at heart" may refer to?
Land of many water snakes - P1VM8L
Have an idea of what "Land of many water snakes" may refer to?
The socks and sandals state - 23IEZ01
Have an idea of what "The socks and sandals state" may refer to?
The crooked governor state - 1PLIT4
This seems to be a reference to Illinois as 4 of their last 7 governors have been convicted for fraud and/or corruption. The colors on the license plates are also identical.
First in foreclosures - 1AVN86
For 2013, this would be New Jersey (2nd place Florida, 3rd place New York). Note that the license plate serial would not be valid for new Jersey...but OTOH it looks like none of the license plate serials match some state's license plate serial format).
The wait and see state - 13NR14
Have an idea of what "The wait and see state" may refer to?
Touch it with a stick state - 2H45LX
The touch it with a stick plate refers to WV, referring to hillbillies being dumb, so when finding dead things they poke at them as pictured in film and TV. The license plate is blue and gold, just like it is in West Virginia also.
The land of loud talkers - SABI7F
Have an idea of what "The land of loud talkers" may refer to?
The bee sting state (dec) - J111A1
Utah is the "bee hive state" (they also has bee hives depicted on license plates at some time).
Home of the other clam chowder (feb) - LTOU12
This may refer to the state of Rhode Island, which has its own style of clam chowder featuring a clear broth rather than the more common cream-based "New England clam chowder".
The pickpocket state - LL158Z
Have an idea of what "The pickpocket state" may refer to?
The sunburn state (aug) - 6HGF17
A pun on Florida's slogan "Sunshine State".
America's second-greatest Carolina - 21PIR9
Have an idea of what "America's second-greates Carolina" may refer to?
Unique left turn laws - 1DXV4
This does indeed seem to be a reference to the "Michigan left", giving us Michigan as the state.
America's Mongolia (jul) - 32UVL9
Have an idea of what "America's Mongolia" may refer to?
Where soda meets pop - 7IDAF1
Have an idea of what "Where soda meets pop" may refer to?
The soda/pop dividing line in NY is somewhere between Syracuse and Rochester.