Ohio/Boundaries/Counties
County borders were originally supplied by the USGS. Those boundaries are not of great precision. Also, that import process created a lot of overlapping ways, and didn't use the admin_level=* key.
Much work has been done on the county boundaries. There is now a boundary relation for each county, and all county boundary ways have been split and merged as necessary so that only one chain of non-overlapping ways defines the boundary between any two adjacent counties. (Along Ohio's border, Ohio's county boundaries were merged with the TIGER-imported state boundary. Generally, the boundaries of counties in adjacent states have not been modified, and remain sourced from imprecise USGS data.)
There are still tasks to be done, however. Where county and city boundaries overlap, they should be merged; the merged boundaries should have admin_level=6, unless of course they're also part of the state boundary, which would be 4. The accuracy of the USGS-sourced boundaries can be improved, by following the endpoints of TIGER data or clues visible in the aerial imagery; these clues might include visible property lines, and especially natural waterways. Check USGS topo maps when in doubt.
Because the TIGER import was conducted county by county, roads ended up disconnected wherever they crossed county lines. Worse, where roads followed the county line (especially in northwestern Ohio), two duplicate roads were imported, each with names and route numbers specific to one side of the road. We've mostly finished fixing the road network along county lines, though some issues are still waiting to be found.
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 county lines without having to conflate two separate databases. Ideally, wherever a county or municipal limit clearly follows a road, river, or edge of a landuse area, we should "weld" the boundary relation to the other feature. For example, where the Butler–Hamilton County line follows Fields-Ertel Road, there is a way
way that belongs to the Butler County
Butler County and Hamilton County Hamilton County boundary relations. It is joined to Fields-Ertel Road Fields-Ertel Road 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.
| Code | Name | Relation | Boundary Source* | City Boundary Merging | TIGER welding |
|---|---|---|---|---|---|
| ADA | Adams | 911255 911255 | KY = T; Bro, Hig, Pik, Sci = U | ||
| ALL | Allen | 911260 911260 | U | ||
| ASD | Ashland | 911247 911247 | U | ||
| ATB | Ashtabula | 350382 350382 | maritime = M; land PA = T; Tru, Gea, land Lak = U | ||
| ATH | Athens | 911269 911269 | U | ||
| AUG | Auglaize | 911251 911251 | U | ||
| BEL | Belmont | 911264 911264 | WV = T; Moe, Nob, Gue, Has, Jef = U | ||
| BRO | Brown | 163283 163283 | KY = T; Cle = Yt; Cli, Hig, Ada = U | Cle | |
| BUT | Butler | 104783 104783 | IN = T; Pre, Mot, partial War = U; partial War, Ham = Yt | partial War, Ham? | |
| CAR | Carroll | 911249 911249 | U | ||
| CHP | Champaign | 180915 180915 | Log, Uni, Mad, Cla = Yt; Mia, She = U | Log, Uni, Mad, Cla | |
| CLA | Clark | 180912 180912 | Chp, Mad, Gre = Yt; Mot, Mia = U | Chp, Mad, Gre | |
| CLE | Clermont | 104779 104779 | KY = T; Bro, Ham = Yt; War = U | Complete | Ham, Bro, KY |
| CLI | Clinton | 104780 104780 | Gre, Fay = Ty; Hig, Bro, War = U | Gre, Fay | |
| COL | Columbiana | 911253 911253 | PA, WV = T; Jef, Car, Sta, Mah = U | ||
| COS | Coshocton | 241687 241687 | Mus, Lic, Kno = Yt; Hol, Tus, Gue = U | Mus, Lic, Kno | |
| CRA | Crawford | 911262 911262 | U | ||
| CUY | Cuyahoga | 350381 350381 | maritime = M; land Lak, Gea, Sum, Med, land Lor = U | ||
| DAR | Darke | 911258 911258 | IN = T; Mer, She, Mia, Mot, Pre = U | ||
| DEF | Defiance | 911265 911265 | IN = T; Wil, Hen, Put, Pau = U | ||
| DEL | Delaware | 178339 178339 | YTt | Fra | Complete |
| ERI | Erie | 350378 350378 | maritime = MT; land Lor, Hur, land San = U | Ott | Ott? |
| FAI | Fairfield | 178391 178391 | Yt | Complete | |
| FAY | Fayette | 270616 270616 | Yt | Complete | |
| FRA | Franklin | 177915 177915 | YTt | Mad, Del | Complete |
| FUL | Fulton | 911263 911263 | MI = T; Luc = Yt; Hen, Wil = U | Luc | Luc |
| GAL | Gallia | 911268 911268 | WV = T; Law, Jac, Vin, Meg = U | ||
| GEA | Geauga | 911256 911256 | U | ||
| GRE | Greene | 104781 104781 | Yt | Complete | |
| GUE | Guernsey | 911270 911270 | U | ||
| HAM | Hamilton | 104784 104784 | KY = T; But, War, Cle, IN = Yt | Complete | Complete |
| HAN | Hancock | 911252 911252 | U | ||
| HAR | Hardin | 911267 911267 | Uni = Yt; Log, Aug, All, Han, Wya, Mar = U | Uni | |
| HAS | Harrison | 911248 911248 | U | ||
| HEN | Henry | 911257 911257 | Luc = Yt; Woo, Put, Def, Wil, Ful = U | Luc | Luc |
| HIG | Highland | 271300 271300 | Fay, Ros = Yt; Pik, Ada, Bro, Cli = U | Fay, Ros | |
| HOC | Hocking | 270614 270614 | Ros, Pic, Fai, Per = Yt; Ath, Vin = U | Ros, Pic, Fai, Per | |
| HOL | Holmes | 911250 911250 | U | ||
| HUR | Huron | 911254 911254 | U | ||
| JAC | Jackson | 911266 911266 | U | ||
| JEF | Jefferson | 911261 911261 | WV = T; Bel, Has, Car, Col = U | ||
| KNO | Knox | 185763 185763 | Cos, Lic, Del, Mrw = Yt; Ric, Asd, Hol = U | Cos, Lic, Del, Mwr | |
| LAK | Lake | 350372 350372 | maritime = M; land Atb, Gea, land Cuy = U | ||
| LAW | Lawrence | 911271 911271 | WV, KY = T; Sci, Jac, Gal = U | ||
| LIC | Licking | 178389 178389 | Yt | Complete | |
| LOG | Logan | 184059 184059 | Uni, Chp = Yt; She, Aug, Har = U | Uni, Chp | |
| LOR | Lorain | 350377 350377 | maritime = M; land Cuy, Med, Asd, Hur, land Eri = U | ||
| LUC | Lucas | 350384 350384 | land Ott, Woo, Hen, Ful, land MI = Yt; maritime = M | Complete | Complete |
| MAD | Madison | 177916 177916 | Yt | Fra | Complete |
| MAH | Mahoning | 911312 911312 | PA = T; Col, Sta, Por, Tru = U | ||
| MAR | Marion | 185761 185761 | Mrw, Del, Uni = Yt; Har, Wya, Cra = U | Mrw, Del, Uni | |
| MED | Medina | 911294 911294 | U | ||
| MEG | Meigs | 911311 911311 | WV = T; Gal, Vin, Ath = U | ||
| MER | Mercer | 911290 911290 | IN = T; Van, Aug, Dar = U | ||
| MIA | Miami | 911306 911306 | U | ||
| MOE | Monroe | 911293 911293 | WV = T; Was, Nob, Bel = U | ||
| MOT | Montgomery | 104782 104782 | Gre = Yt; War, But, Pre, Dar, Mia, Cla = U | Gre | |
| MRG | Morgan | 911302 911302 | U | ||
| MRW | Morrow | 185762 185762 | Kno, Del, Mar = Yt; Cra, Ric = U | Kno, Del, Mar | |
| MUS | Muskingum | 241688 241688 | Per, Lic, Cos = Yt; Gue, Nob, Mrg = U | Per, Lic, Cos | |
| NOB | Noble | 911300 911300 | U | ||
| OTT | Ottawa | 350380 350380 | land Luc = Yt; maritime = MT; land San, Woo = U | Luc, Eri | Luc, Eri? |
| PAU | Paulding | 911314 911314 | IN = T; Def, Put, Van = U | ||
| PER | Perry | 241689 241689 | Hoc, Fai, Lic, Mus = Yt; Mrg, Ath = U | Hoc, Fai, Lic, Mus | |
| PIC | Pickaway | 178392 178392 | Yt | Complete | |
| PIK | Pike | 911307 911307 | U | ||
| POR | Portage | 911288 911288 | U | ||
| PRE | Preble | 911259 911259 | IN = T; Dar, Mot, But = U | ||
| PUT | Putnam | 911301 911301 | U | ||
| RIC | Richland | 911309 911309 | U | ||
| ROS | Ross | 270615 270615 | Hig, Fay, Pic, Hoc = Yt; Vin, Jac, Pik = U | Hig, Fay, Pic, Hoc | |
| SAN | Sandusky | 911303 911303 | maritime = M; land Eri, Hur, Sen, Woo, land Ott = U | ||
| SEN | Seneca | 911297 911297 | U | ||
| SCI | Scioto | 911291 911291 | KY = T; Ada, Pik, Jac, Law = U | ||
| SHE | Shelby | 911292 911292 | U | ||
| STA | Stark | 911298 911298 | U | ||
| SUM | Summit | 911310 911310 | U | ||
| TRU | Trumbull | 911299 911299 | PA = T; Mah, Por, Gea, Atb = U | ||
| TUS | Tuscarawas | 911305 911305 | U | ||
| UNI | Union | 178021 178021 | Yt | Complete | |
| VAN | Van Wert | 911295 911295 | IN = T; Pau, Put, All, Aug, Mer = U | ||
| VIN | Vinton | 911308 911308 | U | ||
| WAR | Warren | 104778 104778 | Ham, partial But, Gre = Yt; partial But, Mot, Cli, Cle = U | Ham, partial But | |
| WAS | Washington | 911289 911289 | WV = T; Ath, Mrg, Nob, Moe = U | ||
| WAY | Wayne | 911304 911304 | U | ||
| WIL | Williams | 911287 911287 | IN, MI = T; Ful, Hen, Def = U | ||
| WOO | Wood | 911313 911313 | Luc = Yt; Ott, San, Sen, Han, Hen = U | Luc | Luc |
| WYA | Wyandot | 911296 911296 | U | ||
*Boundary Sources:
- U: USGS data import
- M: USGS topographic map
- T: TIGER data import (state/municipality borders)
- Y: Yahoo! or other acceptable aerial imagery
- t: Implied from non-boundary TIGER data