The same immigration agents who, day after day, encouraged the cleaning lady at their office to become a citizen on Friday saw Blanca Ruiz finally take the oath. Ruiz, a native of Mexico, was among nearly 500 immigrants sworn in as U.S. citizens at this year's largest naturalization ceremony in Tucson. The ceremony recognized Citizenship Day, which is celebrated today. The Tucson Convention Center teemed with proud new citizens from 69 countries. Mexico contributed the most people, close to 300. Ruiz, who is from the state of Chihuahua in northern Mexico, took it all in. At 60, she almost couldn't...