3. Jurisdictional Boundaries

Even though zones are based on mathematical projections,their boundaries generally coincide with counties or parishes. For example, Wisconsin uses three conic-base zones: South, Central, and North. Figure G-3 shows these zones overlaid on a map of the counties.

Figure G-3
Wisconsin SPC Zones and Counties

While C&GS/NGS mathematically designed the zones, states decided their jurisdiction limits. Keeping counties or parishes entirely within a single zone supported uniform surveying and mapping activities. This became increasingly important with adoption of geographic information systems at local jurisdictional levels.