20,000 new suspects per month. You may be one of them.

The TSA's terrorist watch list is approaching a million entries. Since many people have the same or similar names, that ensnares several million people. The ACLU has a good discussion of the implications.

IEEE's The Risk Factor has a good overview and summary.

If you are unlucky enough to get on this list, it's probably easier to stop traveling than to get off the list. And safer.