The trouble is that you're localizing the variables in one block, then trying to use them in another. Since the variables exist in do_msalist(), they don't exist in by_americentric().

You need to have the variables accessible by by_americentric(). There are a few ways to do this. One way is to put both of the subroutines inside an enclosing block, like this:

{
    my (%country, %state, %msaname);

sub do_msalist {

    my @msakeys = @_;

    foreach(sort by_americentric @msakeys) { 
        #...
    }

}

sub by_americentric {
    $country{$b} cmp $country{$a}
    or
        $state{$a} cmp $state{$b}
    or
        $msaname{$a} cmp $msaname{$b}
    or
        $a <=> $b;
}

}
[download]

Or, you can define the associative arrays as package variables with 'use vars'. Or you can just put by_americentric in as a blockin do_msalist, and call it that way:

sub do_msalist {

    my @msakeys = @_;

    foreach(sort {
    $country{$b} cmp $country{$a}
    or
        $state{$a} cmp $state{$b}
    or
        $msaname{$a} cmp $msaname{$b}
    or
        $a <=> $b;
} @msakeys) { 
        #...
    }

}
[download]

That'll work if you only call by_americentric right there. But it's harder to read.

stephen