The National Counterterrorism Center maintains a database – Terrorist Identities Datamart Environment (TIDE) – currently containing 875,000 names. Among them were the underwear bomber Umar Farouk Abdulmutallab and Tamerlan Tsarnaev, the older of the Boston Marathon bombers. I think the haystack is getting so big it will eventually be impossible to find the needles, and we will be less free as a result.
With that many people on a watch list it becomes useless. From what I understand they have several lists to boot. As you said, the haystack is getting too big….