A redacted ledger with names of suspected terrorists. Decades ago, names of suspected terrorists were kept in a rolodex and in notebooks, according to redacted government photographs. The Associated Press has learned that a U.S. government database of known or suspected terrorists doubled in size in recent years. The National Counterterrorism Center says there were 1.1 million people in the database at the end of 2013. Of those, 25,000 are U.S. citizens or legal permanent residents. There were about 550,000 people in the database in March 2010. The Terrorist Identities Datamart Environment, called "TIDE," is a huge, classified database of people who are known to be terrorists, are suspected of having ties to terrorism, or in some cases related to or are associates of known or suspected terrorists. It feeds to smaller lists that restrict peoples' abilities to travel on commercial airlines to or within the U.S.