On Friday, Mr. Dingell, 86, the former Democratic powerhouse who asserted jurisdiction over vast expanses of federal policy as the intimidating chairman of the Energy and Commerce Committee, will become the longest-serving member of Congress in history with his 20,997th day as a representative, surpassing the record held by Senator Robert C. Byrd, Democrat of West Virginia.

 

Unlike Mr. Byrd, who rose from poverty in the Appalachian coalfields, Mr. Dingell was, in his own words, “a child of the House.” He made his first appearance on the House floor at the age of 6, when his father was elected in 1933; he went on to become a Congressional page; and after his father died in 1955 he successfully ran for his seat at the age of 29....