How does RCI demand work in a region?
In region play, RCI demand is shared across all your cities. For example, if you have one city that has started demand for IHT (high tech industry), you can start a new neighboring city, zone industrial, make a road connection to your first city and high-tech will start to pop up in your new city, satisfying the demand of the city that it is connected to. Using this concept you can create ’bedroom communities’: wait for your residential demand to climb in one city, then start a neighboring city, connect with to your first city by road, and zone residential and watch as your sims move in to live in your new city and commute to the other city to work.