US copper futures ended slightly higher on Monday, rebounding from last week's losses, helped by technical support. Copper for September delivery rose 0.05 cents to close at $3.2915 per lb on the COMEX metals division of the New York Mercantile Exchange. Range extended down from $3.3310 to $3.2710. COMEX estimated final copper futures volume at 22,919 lots. Open interest down 1,745 lots at 139,416 contracts as of August 20.