How did you reference the appended tables when you needed historical changed data?

As far as the zip codes go, i was thinking of backwards compatibility on the application side. In other words, i was going to do a data drill down  starting @ country first, then region, then state etc... until i got to zip where there would be a set amount of zip codes available. Still not sure though. I have my tables set up that way so that one is related to the other country to region, region to state, state to state region, state region to county, and county to city. But in the membership example on that data model, the guy puts the country and state in the address table, yet still shows the relationship between country and state. I think thats where i'm getting confused.

Thanks again for you help!!!

David