Originally Posted by WillCAD

The feds have their own databases, collected from numerous sources. Without the state databases, their ability to locate, identify, and/or track people via facial recog would be much more limited, but they could still do it.

Photo and fingerprint DBs the feds keep include passports, trusted travelers, federal employees, contractors/consultants, anyone holding any sort of clearance, anyone who works on a federal installation, anyone who has ever been arrested by a federal law enforcement agency, and of course current and former members of the armed forces (I don't know how far back the digital photos and prints go, but I believe they've been doing it digitally for at least 15 years, probably more like 20, and the old hard copies may have been digitized as far back as the 1980s or 1990s). I would hazard a guess that anyone holding any sort of federal license for occupations involving manufacture, use, or transport of firearms, explosives, toxic substances, or radioactive materials, would probably have their photos and prints in a BATF, DOE, or DOT database somewhere. That total only represents a fraction of the populace, but it's still millions of people. And if a photo is in a federal DB, it can be used by a federal law enforcement agency.