There are various sources for Wisconsin state boundary data, but quality levels can be quite variable. In addition, most state boundary representations are generalized and will not necessarily match other features, such as hydrography, at the very largest map scales.
The most authoritative description of the state boundary is in the Wisconsin constitution. However, this description refers to features that are no longer extant, such as “the Indian village, according to Nicollet’s map” or to features that have an uncertain location, such as the “center of the main channel” of the Mississippi River. Also, this is a textual description of the boundary rather than a map or geospatial database.
One source of authoritative boundary data for Wisconsin is the US Census Bureau. A more detailed boundary is available from the Wisconsin Department of Natural Resources Open Data Site. The DNR boundary was developed from the US Census Bureau dataset with input from the Wisconsin Geological and Natural History Survey (WGNHS). It uses 1:24,000-scale hydrography data as the source of linework for portions of the boundary defined by shorelines, and 1:24,000-scale Landnet data as the source of linework for most of the border between Wisconsin and Illinois. The dataset is a generalized representation of the state boundary and is not intended as a representation of the legal boundary.
For very small-scale maps users can also make use of the SCO’s state outline maps, available in various image formats as well as for desktop illustration software.
A high-precision authoritative state boundary layer built from detailed parcel-level data does not yet exist. The statewide parcel database could be used to derive such a layer, although some location inaccuracies would exist across county boundaries. There is also currently (2017) a boundary dispute with Minnesota over the exact location of the boundary in portions of the Mississippi River.
The US Census Bureau is the authoritative national source of state boundary data. Under the federal Office of Management and Budget Circular No. A-16 (Revised), the Census Bureau is the lead agency responsible for boundary data nation-wide. Boundary data collected by the Census Bureau reflects official boundaries of federal, state, local, and tribal governments as reported by designated officials at that appropriate level of government.
There are several versions of state boundaries produced by the Census.
An annual state boundary file is produced as part of the Census Bureau’s cartographic boundary series. Shapefiles can be downloaded at different scales (1:500,000 to 1:20,000,000). These cartographic boundary files are generalized representations intended for small-scale thematic mapping. They are “cartographically ready” in that coastlines and islands have been superimposed on top in a cookie-cutter manner.
A second option is the TIGER/Line file, which can also be downloaded. This representation is less generalized than the cartographic boundary file, but it is not “cartographically ready” in that it shows the state’s boundaries extending into the Great Lakes. Islands and coastlines may be missing. Users who need to show these features on a map will need to incorporate other thematic layers into their map. Full documentation of Census Bureau TIGER/Line files is available.
For historical county data the definitive source is the Newberry Library’s Atlas of Historical County Boundaries.
If you are having trouble locating State Boundaries in Wisconsin or need further help, please contact us via e-Mail or at (608) 262-3065.