preg-split regular expression
===

I am having the input string of 

Aspen,Colorado-USA

I want to split it by using preg-split

i want this output:

Array ( [0] => Las Vegas [1] => NV [2] => US )

I have used like this  

    $input=Aspen,Colorado-USA;
    $out=preg_split( "%[^a-zA-Z\s]%",$input);

is it correct? I want to know efficient way to do this.