Matching Many Patterns at Once

A better way:

        $pat = join '|', map "($_)", @state_pat;

$pat now looks like:

        (Alaska)|(Alabama)|...|(Wyo(?:\.|ming)?)

Now use:

        my @matchlist;        
        if (@matchlist = ($input =~ /$pat/o)) {
          my $i = 0;
          ++$i until defined $matchlist[$i];
          return $state_abbr[$i];
        } else {
          return;
        }

Caution: Important to use (?:...) instead of (...) in subpatterns.