Economic zone

Economic zones (sometimes referred to as ecozones or EZ's) are groupings of regions in close proximity that separate heir country in to various "super-regions". Basically, they represent what in the real world is considered an appropriate distance for people to commute to work, and / or purchase goods. One easily-described example would be the American real-world region of New England. Comprised of the states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut, all of which are fairly small in size and close-knit economically, New England is a perfect real-world example. People who work in Rhode Island may easily commute to work from neighboring cities in Connecticut or Massachusetts, and also shop in either state.

It is worth noting that some countries (or even several very small countries) can be comprised of a single economic zone. It should also be noted that regions that are part of the same economic zone, but are separated by an international border, are still held to be in the same economic zone. Any "transport" costs (see below) will not apply, but citizens will not be able to work across the border, nor will they be able to buy goods made on the other side of said border. Likewise, any import / export taxes will still apply.

Limitations

 * Citizens who hold a job must hold it with a company located in the same economic zone in which they reside.
 * Citizens can only work at companies located in the same economic zone in which they reside, even if they own the company. (For example, a citizen living in New York cannot work at a company he/she owns in Florida.

Calculations
Economic zones are used to calculate the costs of several actions in Populus.

Transport Costs
Products can be purchased on the shop of the country in which they are being sold, regardless of economic zone. However, it is worth noting that goods from further-off economic zones have higher costs associated with them, to reflect the cost of transporting them across the nation. That cost can be calculated using the formula:

Moving Costs
When a citizen moves from one region to another, the cost of doing so is also calculated using the economic zones being moved from and to.