nobody answered my question though
so u can connect cities together or how does this work
Yea basically all cities in a region are connected via highway and rail. Each city within the region can share services and resources with each other, and help spur growth.
For instance, if I create an industry-heavy city it would make sense for me to create a big garbage-collection operation and a sewage treatment plant and take all of y'all garbage and sewage. So someone who creates a beautiful tourist city that doesn't want those types of services in their city can just get their coverage from me.
Some of your residents can also come work in my industry if they can't find enough jobs in their own cities, and demand for industry in your city wouldn't be as high because there is more of that in my city. I could buy my water from your city, and you could buy your power from me.
You could provide a big fire department and police department to provide crime and fire protection for me and I wouldn't have to build those things as long as you send enough coverage my way.
Someone else could build a big university and your sims could go to their city to get educated. You could build a bus and train network to make sure those students can get to that dude's cities because the buses will help sims commute between cities.
And all the cities in the region share city hall departments. If I built a department of utilities in my city, you get the benefits of that, and vice versa if you were to build a department of education or department of transportation.
literally everything is intertwined. sh*t will be crazy.