National Foster to Adopt Agency?

I've recently begun the process of foster to adopt in my county. How the county is set up is that the only children that they will place you with are children within that county. With the high amount of potential parents on the wait list I have been told that it will take some time, not because of the restrictions but due to the amount of children in need of a home within the county. I am not so concerned with it taking time but more interested in looking at other options outside of the county because there just might be a child who is meant to be with us outside our little county. I was curious if there was a national foster to adopt agency to help in the process if I wanted to go out of county, or even out of state. I have read up on interstate adoption but have yet to find an agency that specializes in this area.