Yeah, I know about the regional thing.
The numbered pieces are identical for the MW (northwest US) area and the SC (California/Nevada) areas. Just the California/Nevada pieces are labeled SC and the northwest US is labeled MW. You can't interchange the two, so I can't buy pieces from MW and combine with my SC piece.
I need SC34. I have SC32.
The rare pieces in the MW game are MW32 and MW34.