This has happen to me three cities in a row. I build up my population to around 2000, they are well educated, I buy water and power everything is going well, i have lots of dirty industry (no where near my residential) and some MI and like two IT also some CO then all of a sudden industry demand drops, and everyone has no jobs, and my whole industry area becomes vacant and everyone moves out? There is still demand for housing but no one will move in. Can anyone help im sick of loosing cities lol thanks G