Your subroutine will accept "AK\n" as a state. Fixing that takes it to 125. But I can beat that with the following 122 character solution (which is what I was trying to figure out when I posted my first): 
sub state{
$_[0]=~/^\w\w\z/&&grep/$_[0]/,'WVTNHINMSCORIDCAKSDE WIALAR MNCTX NVAZ'
+,'FLGAILKTKYMAMDMEMIMOMTNDNENJNYOHOKPAUTWAWY'=~/../g
}

[download]
OTOH I can improve your idea down to 119: 
sub state {
pop=~/^([CGILPVW]A|[CKUV]T|[HRW]I|A[KLRZ]|CO|DC|DE|FL|I[DLN]|KS|KY|M[A
+DEINOST]|N[CDEHJMVY]|O[HKR]|SC|SD|TN|TX|WV|WY)\z/
}

[download]

In reply to Re (tilly) 4: Golf challange: match U.S. State names by tilly
in thread Golf challange: match U.S. State names by John M. Dlugosz

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