WASHINGTON (Reuters) - The U.S. State Department, reacting to Spanish efforts to block a Catalan independence bid, said on Friday that Catalonia is an integral part of Spain and Washington backs Madrid s efforts to keep the country united.  Catalonia is an integral part of Spain, and the United States supports the Spanish government s constitutional measures to keep Spain strong and united,  State Department spokeswoman Heather Nauert said in a statement. 