Mark,
The correct answer to your question is yes, no and maybe. Each Harrah's Casino has a 3 digit location code. Players that initially signup for a card at a location get a card with that location number as the first 3 digits. If you subsequently get a reissue of a card at another Harrah's location, the number on the card will be the same as on your initial card issued at the original location. Example: Signup at Atlantic City and get a card starting with 157. Go to Cherokee and ask for another card you get the same number starting with 157, not a card starting with 107. Providing of course they find your name / number in the system.
So, the first 3 digits may be "from" the location identified but could also be "from" another location. There is no real way to be sure which location a card is "from" based on the first 3 digits.
My initail card is from AC (157). I have the same number on cards issued at Cherokee, St Louis, St Charles, Metropolis, Skagit Valley, New Orleans, East Chicago, Joliet and others.
Note: I am not knocking anyone that collects the cards based on the first 3 digits. I'm just pointing out that the first 3 digits Do Not necessarily represent location.
Paul