Using population statistics supplied by the respondents, it can be seen that there is a wide variation in ward sizes. The average size was 40,047. Three of the four largest American cities in the survey have wards with over 130,000 people in them, and Edmonton stands out among Canadian cities with wards of over 100,000. On the other hand, one very large city, Montreal, has wards of just over 20,000 people, and two mid-sized American cities, Nashville and Baltimore, report wards of approximately 14,000 and 28,000 respectively. How ward boundaries are determined and revised A variety of methods are used to determine ward boundaries.
Population is almost always a factor.
Most ward boundaries are revised on a regular basis, notably in the United States where many cities revise their boundaries every ten years using the population data provided by the national census. Well over half of the cities surveyed have changed their system of election in one way or another in the past 25 years, and four have done so in the past 5 years. In a majority of cases, the change has been to a mixed system. This fits with Renner's study of U.S. municipalities, which notes that the number of at-large systems has been falling since 1981, while the number of mixed systems has been rising. Pure ward systems have stayed static in that time.