I realized a while back exactly why the 30 Cities goal spawned on screen... it has something to do with scenario-specific goals listed in the instruction manual. I have accordingly switched the name and instructions around that category to make it more in line with what it is you are doing.

You are now able to accomplish this goal in any of the first 4 scenarios (scenario 5 has no specific objective other than to beat the game). While I doubt any scenario is faster than the first, now y'all can try if you want :)