Comment by l33tman

I don't know about the US but in other countries it is definitely by design that the departments and their data are separate. It is far too easy to abuse gathering and joining data on people otherwise. History did teach us these lessons, and it's continuously visible as well today, fortunately at small scales just because they are separate.

It would truly be a nightmare scenario to have all government databases under a single potentially corrupt roof or having someone with access to all of them cough.