Thanks Doyle. I was confused about that underwater part. And I completely forgot about the trans-Atlantic cable. Silly me.

But isn't Clarksville on the north side of the Arkansas? Is it possible the line crossed the river twice, once at Clarksville and once at Van Buren? Sounds unduly complicated and troublesome to me, but it would explain why the Clarksville operator occasionally got involved in the message traffic between Little Rock and Van Buren/Fort Smith.