Inexplicably, township lines were entirely omitted from the TIGER import, even though TIGER has extensive township border data. That data is often quite inaccurate anyways, so it's up to us to draw the townships by hand. Note that the townships described on this page are civil townships, even though in Ohio they almost always correspond to survey townships.
Finding a township line
The first step in mapping a township boundary depends on the part of the state:
- In counties surveyed under the Public Land Survey System, or in the Connecticut Western Reserve, aerial imagery often shows prominent roads that run through the county in a roughly 5–6 mile grid. Even where there aren't roads, you can still make out different farms along these lines.
- In counties surveyed using the older metes and bounds method, such as in the Virginia Military District, the first step is often to identify prominent natural features that might have served as an obvious township line in the past, then go out and see whether there's a township welcome sign anywhere near there. For example, the smallest of rivers often serve as township lines because they were significant obstacles back when it took awhile to get to the nearest bridge.
Now fire up your favorite editor and switch to the USGS Topographic Maps layer. This layer displays a bunch of public domain topographic maps from the USGS laid out side-by-side. Township boundaries are generally shown as black dashed lines. They can be hard to spot, especially where they are overlaid on roads and creeks, so it helps to keep the above observations in mind.
Note that the topo layer can be slightly misaligned in places. It helps to switch back to aerial photography once in awhile, as a sanity check. If you know the general vicinity of a township line, you may also be able to spot a change in pavement quality where one township has repaved their road up to the township line.
Some editors have features that make it easy to see the topo layer at the same time you edit features on top of it. For example, if you use Potlatch 2, press D to make OSM features translucent; you can also turn on the "Show floating window" option in the Layers menu for a side-by-side display. In iD, press W to toggle wireframe mode.
Finally, you may be able to convince your county's engineer's office to let OSM copy the township lines from their official road map. But whatever the case, whenever possible, OSM prefers on-the-ground knowledge to simply copying from an existing map.
Mapping a township line
Township boundary relations are tagged with type=boundary + boundary=administrative + border_type=township + admin_level=7 + name=*. You may also specify a Wikipedia article or a website URL. See WikiProject United States/Boundaries for a comparison of admin_level=* usage in each state.
In Ohio, townships never extend past county lines. A city or village is subordinate to its township unless it withdraws from the township by establishing a coextensive paper township. (If the municipality then expands into an additional county, an additional paper township must be established.)
Do not map paper townships. Boundary relations should exclude the paper townships of municipalities that have withdrawn. In other words, the township starts at the welcome sign, not necessarily where the township was historically. In cases where a withdrawn municipality has annexed some land but its paper township's boundaries have not been updated – it happens sometimes – the adjacent real township should overlap the municipality. If the paper township's name does not match its municipality's name, tag the municipality's relation with the paper township's name in alt_name=*.
One of OSM's strengths is that all types of data coexist in the same database, allowing you to (for instance) find roads that run along township lines without having to conflate two separate databases. Ideally, wherever a township limit clearly follows a road, river, or edge of a landuse area, you should "weld" the boundary relation to the other feature. For example, in Butler County, the border between Liberty and West Chester townships follows Hamilton-Mason Road. There is athat belongs to the 2739509 and 2739508 boundary relations. (In the event this border is also a city or county border, the way can belong to those relations as well.) This boundary way is joined to at every node along the road. (In Potlatch, press F repeatedly to "follow" the road you're welding the boundary to.) Please do not make the road itself a member of the boundary relations.
At the center of some townships lies a population center of the same name. The GNIS import introduced place=town POIs to represent these population centers. Each POI represents a settlement with an indefinite boundary, rather than the administrative unit represented by the boundary relation, so the name=* tag should not contain the word "Township".
As of July 2017, most of the progress has been in northwestern, north-central, and southwestern Ohio. Use this Overpass turbo query to find correctly tagged townships.
|County code||County name||Total townships||Townships mapped||Notes|
|ALL||Allen||2|| Jackson Township in progress
Auglaize Township largely completed
|GEA||Geauga||16||16||Incorrectly tagged; also excludes CDPs from townships|
|PIC||Pickaway||15||15||Should be admin_level=7, not 8|
|WAY||Wayne||16||5||Completed Congress Twp., Plain Twp., Paint Twp., Clinton Twp., and Chester Twp.|