Consider the challenges posed by the dynamics of a regional population such as that in Central Ontario. In a region of more than 7.6 million people there are approximately 2.5 million households (defined here as the primary units of collective social consumption), who occupy a roughly equivalent number of dwelling units, and drive more than 4.3 million vehicles. These households in turn are linked through complex local labour markets to perhaps 4 million jobs distributed among 100,000 or more work locations. Moreover, both people and jobs tend to move, some frequently. In parallel, the Central Ontario region welcomes between 80,000 and 100,000 overseas immigrants each year. A smaller but significant number emigrate. In addition, every year some 50,000 people move in from other regions within the province and the rest of Canada, and a similar number move out. Natural increase, births minus deaths, in turn adds another 40,000 people.
The argument here, in essence, is that over a typical ten-year planning horizon, as many as one million people may be new to the Central Ontario Zone at the end of the period; and half a million may have moved away. Moreover, among continuing residents, between 15 to 18% of the population, or over 1.2 million people, change their place of residence within the Central Ontario Zone. There is no such thing as a fixed population or labour force; there is no fixed social geography. As a consequence, planning must deal with anticipating flows of people as much as it does managing the existing population.