>>14Most econometrics is retroactive, so that's the simple linear equations you are seeing. You need to look at the forecasting and complex systems modeling side.
That gets more into things like autoregressive models, Gauss-Markov processes, OLS Asymptotics, multicollinearity, heteroscedasticity, etc.
The best thing to do is to look for some online public econometric data about a population that's close to what your city's initial state is like and mess around with the models that forecast its various states.
Markov chains work well at first but hit a limit fairly quickly, I suggest looking into something like ART-2 (Adaptive Resonance Theory 2) as a start for simple forecasting, or Hidden Markov Models which are more complicated but yield better results in most cases.