Tried searching for this information elsewhere and couldn't find a clear answer in the TIGER documentation, so I thought I'd turn to you good folks.
Obviously, congressional districts can cut across counties and 'cities', but which census geography boundaries do they preserve (if any)? Tracts? Block Groups? Blocks?
I suppose I'm most interested in learning what is the largest type of census geography whose boundaries are preserved by congressional districts in every case.
Thanks in advance!