The following table is a summary of the tags to use for county boundary relations.
|gnis:feature_id||see table below|
|gnis:county_id||see table below|
|gnis:state_id||18||18 is for Indiana|
County borders were originally supplied by the USGS. Those boundaries are not of great precision. Also, the import process created a lot of overlapping ways, and didn't use the admin_level=* key.
The following counties' borders are being assigned to relations, merged with adjacent county borders rather than overlapping them.
When "TIGERifying" county borders, please ensure that any road crossing a county line is joined up properly. The roads seem to have been imported county-by-county, causing the roads to be disconnected. In particular, "county line roads" are usually duplicated, so one county's copy should be deleted and that county's roads should be reconnected to the remaining copy.
See List of Indiana counties for more information on Indiana counties.