Hold up hold up hold up, you can link ur city with other people in the same regions? Whaaaaat, dude's talking about "once someone puts up an airport in my region ill get more police helicopters"
Yeah you work with other people in the region. You can share services like garbage, fire and police, etc. Also if you have a university in your city, someone else in your region can use as well so they don't have to build it. I don't know about an airport increasing police helicopters though.
You can also play by yourself and make your region private and just build through out, or join a public region.