You might be able to achieve this in an easier way with the Asana API, Zapier (or similar), Flowsana (@Phil_Seeman), or importing a CSV.
But I’d ask: Must these be projects? Sounds unwieldy. Could they work as tasks with subtasks? A custom field for City? It’s too much to try to answer in a thread like this (I do this as a consultant for clients), but if you’d consider tasks instead of projects, see: