Ontario municipalities may be single-tier (e.g., Toronto, Hamilton, Barrie) or two-tier. In the latter category, the upper tier is either a county (such as Brant or Wellington) or a regional municipality (such as Halton or Waterloo).
An upper-tier municipality is one formed by two or more lower-tier municipalities. Municipal responsibilities set out under the Municipal Act and other Provincial legislation are split between the upper-tier and lower-tier municipalities.
A single-tier municipality is one that does not form part of an upper-tier municipality for municipal purposes and assumes all municipal responsibilities set out under the Municipal Act and other Provincial legislation.
Mapping Source:
Municipal Boundaries of Ontario 2004, Ministry of Municipal Affairs and Housing, Ministry of Natural Resources, Statistics Canada.
Additional Information:
Statistics Canada boundary files: http://geodepot.statcan.gc.ca/2006/180506051805140305/06180505162102/92-160-072305/2006001/200503081409030112-eng.htm