SimCity Inter city coal trade

My end goal is to create a tech city. The very first city I created I tried this, but soon ran into resource problems.

I then started a new region, my first city was mining. When I got to the point where I could smelt, I wanted to start creating alloys (for the later tech city), but of course I needed coal. So I started a second city that just mines coal. All good so far. I have two cities, one mines ore, the other mines coal.

At this point I want to send the coal I mine from city 2 to city 1, instead of having to buy it. But for the life of me I can't figure out how to do this. I have searched far and wide. Please Stack Exchange, help me out, it's very frustrating.

Thank you