Not sure from your question how Oregon works in ….
But there is a Robert Cowan in Benton County, Oregon Territory in 1850
Robert Cowan, 27, farmer, b. Scotland
Caroline, 25, Missouri
Mary, 5, Missouri
Emeline, 3, Missouri
James S., 1, O.T. [Oklahoma Territory]
Thomas, 45, Scotland
Oliver Jeffries, 38, wagon maker, Pennsylvania
EDIT - sorry, meant to say O.T. = Oregon or Oklahoma Territory