My main city has been going from 190,000 to 205,000 and I face unemployment problems in my newer buildings. Most of the time they say, " Abandoned due to commute time." Well if your facing this issue in your cities, listen up. Once your city reaches a population of about 50,000 to 100,000, it's time to create an elevated rail or monorail system. Whem your city reaches about 120,000 to 150,000 in population, create both systems in your city. Then when you are facing unemployment and commute time problems, extend one or both of those systems out into other cities until there is one system in the entire region. Other systems such as buses and subways should be built early in the stages of your city's development. Railroads should be built when your city reaches around 20,000 to 50,000 in population and/ or when industrial frieght trips are too long.