How do districts work?
From now on, when you load the game you will see your entire City, which includes all 9 districts. When on this screen, your City Name and Total Population (population of all districts added together) will be shown at the top right corner. Hovering over each district will show that individual district's population. At this time, there is no way to share population or happiness across all districts.
Right now, only two districts are available to be opened, the original and the new Southeast district. All other districts will appear as locked, and the requirements will not be made available until we update the game to unlock them.
If you would like to link roads from one district to another, unfortunately that is not supported yet. You are also only able to look at one district at a time at the closest level, meaning you can only zoom in to one district to edit and collect at one time. When you are at this level you will not be able to see any other districts.
While you cannot share population and happiness across all districts, there are some things that can be shared. All of your items and buildings, for example, can be moved between districts. This includes factories, residences, leisure items and more. Your total population (population of all districts added together) will be the counted for unlocking more factories.
If you want to move between districts, you can click on the green map icon at the top right side of the page. When you get to the large map view, click on the district you wish to visit.
[Via PlayDom Helpdesk]