state pulldown menu

I am wondering why the pulldown for the state on the shipping section of the One page checkout is prefilled with the state of the billing address. We have had the issue come up frequently with all our Christmas orders since so many of them ship to a different state than the billing address. Customers are having trouble getting shipping rates since the state and zip code don't match when they overlook the default address.  I realize that customers should be expected to change this but it really can become invisible to them and I have had several that told me they never noticed it.

 Can I change this so that it is blank until they enter what they need? If so how do I do that?