Legal Question in Real Estate Law in Missouri

You did not indicate what you meant by 'claim one half the fence" so not sure what you're really asking. Twenty years is long enough to adversely possess land. Perhaps there was an easement for the fence. If you think your new neighbor will be suing you, you probably need to consult direclty wiht a real estate or geenral civil practice attorney in your area. If not, perhaps you can repost with a more facts, or more specific question.

Good luck