'Downton Abbey' will be returning soon for Season Three (Okay, okay - January) and the big excitement is the arrival of Shirley MacLaine as Countess Grantham's American mother. She'll be coming over from America within the show, and it looks like someone from the Crawley family moved to the United States.
In an episode of 'Longmire', a man named Ed Crawley was mauled to death by a bear, a premeditated attack engineered by one of Crawley's enemies.
It could be that Crawley was descended from Patrick Crawley, who once was the heir to the Grantham title. But he was presumed to have died on board the Titanic. A man claiming to be Patrick Crawley showed up among the horribly disfigured patients when Downton Abbey was used as a recuperating hospital during World War One. He claimed to have survived the Titanic and ended up in Canada with amnesia. (It was never conclusively determined if this patient was really Patrick Crawley or not.)
Maybe he fathered a son before he shipped off to war. Maybe that son journeyed west once he fond out his "real" last name and settled in Wyoming.