No, that is pretty far away. I thought maybe her old home was much closer to yours. I'd say your best bet is asking around to find out if there's other flocks nearby she might have joined. I accidentally stole someone's duck who had wandered too far from its home and I thought was an abandoned...
Was she a friendly enough chicken that somebody could have caught her? Or was she pretty independent? Chickens naturally want to be in a flock, so I would think that she would come back to yours if she doesn't find another flock to join. You asked how far chickens can roam- she could have gone...
To answer your question about a lost pet resource, does your town have a local Facebook page? Mine does, and that's where people post lost/found animals. Also contact any local animal rescue groups, if somebody found your chicken, they may take her there. Are there any other people with chickens...