I've got a little mining/drilling city up and running (including trade depots, refinery, petroleum hq, etc). Of course due to the area needed for the drilling/mining my RCI is always in demand. My daily budget has dwindled into the red, -$2k - 4k. However, the drilling/mining/trade operation (+$200k/month) is going well and overall I'm getting a positive income stream. Not sure how the time frame plays a part in that as well.
It looks like the income from city specializations are separate from the operational budget of the city? Can anybody confirm that? I wish they would include it together, so you could really see everything balance.