On his Facebook stream, first district congressional candidate Russ Fulcher, of Meridian, has posted an item noting he has always lived in that district. And: “Fun Fact: Russ Fulcher’s family has lived in what is now Idaho’s first Congressional District since 1886, four years before Idaho became a state.”

He is making more than a biographical point. His chief opponent, former attorney general and lieutenant governor David Leroy, currently lives outside the district. Leroy is not far from it;...