Hi @moneykidder it should be fairly easy to track at the outset, not many campaigns of this magnitude will be happening in Durban, South Africa at this juncture of the Beta phase. If the blockchain can be interrogated for the location of the IP addresses used in signing up, then you will have a good idea of the number of new signups the billboards achieved. The only other way is to receive support from the devs of Steemit itself to create a referral code that can be used on signup.I will also chat to the billboard agency for suggestions.