Quote Originally Posted by Ironside
What I don't get is that isn't like almost all that info already known by the state?
Not necessarily. There is no requirement for anyone to inform the state when they move. For voting purposes, it does not matter where you were born, etc., only where you live right now. It is entirely possible for a person to move from one state to another without ever registering the move with any government. This changes the population distribution of the various states, which has an impact on the number of Representatives they have in Congress.

In addition, there are so many levels of local, state, and federal governance that a lot of information simply cannot be gathered together easily in one central source. Things like old birth certificates are still only recorded on paper, rather than digitally, thus making it essentially impossible for the federal government to get a hold of them all. While drivers license information is probably accessible by the states, that doesn't take into account the large number of people who do not hold drivers licenses. As absurd as it may sound, it's probably easier to do a national poll every 10 years than to surmount the legal and bureaucratic hurdles that would be required to get this information from existing sources.