Mary became sick with cholera en route for America, and died while on the river near St. Louis, Mo. She was buried on the banks of the river. At a later date a search was made for her grave but the river had changed its course and her grave was never found. On a subsequent trip back to Swaledale, Robert Bonson remarried to Mahala Kearton Clarkson and returned to America........but eventually returned to Swaledale and is buried at Low Row. Mary and her demise is mentioned in the book "The Dalesmen of the Mississippi" by David Morris.