Although population aging on a national scale has received much attention in Canada, its geographical dimensions have not. This paper examines the demographic processes that underlie population aging at the provincial and metropolitan scales for the periods 1991 to 1996 and 1996 to 2001. We differentiate between the effects of aging-in-place and net migration on population aging. We also examine the relationships between the various measures of aging and the social and economic characteristics of metropolitan areas over the two periods. While aging-in-place is the dominant force in population aging, net migration is more volatile and more likely to produce shifts in the trajectory of aging. Out-migration of the young from areas with weak local economies is a particularly important contributor to aging. British Columbia exhibited a sharp increase in aging in the latter part of the 1990s as net in-migration of younger populations declined, while a number of smaller, resource-based, urban communities also exhibited aging, as out-migration of the young accelerated.