By almost every metric, Illinois' population is sharply declining, largely because residents are fleeing the state. The Tribune surveyed dozens of former residents who've left within the last five years, and each offered their own list of reasons for doing so. Common reasons include high taxes, the state budget stalemate, crime, the unemployment rate and the weather. Census data released Thursday suggest the root of the problem is in the Chicago metropolitan area, which in 2015 saw its first population decline since at least 1990.