A population centre, in Canadian census data, is a populated place, or a cluster of interrelated populated places, which meet the demographic characteristics of an urban area. A population centre has a population of at least 1,000 and a population density of no fewer than 400 people per square kilometre. Population centres are not the same thing as urban municipalities. For example, the city of St. Albert is legally separate from Edmonton, but they are part of the same population centre.