Bing Aerial Imagery was used to retrace the riverbanks. Esri World shows the river running higher than average.

The county line is within the river area. Arnold Township extends to the county line. The City of Arnold extends to the river banks afaict.

Also added some natural=tree.

This only affected Missouri.

Changeset #102703929 stripped this name from MO W for some reason. It's totally fine for a route to be given both a road name and a state letter designation.

I noticed this in the history of one of the ways for MO W (IIRC it was a name_1 key).

I verified the concurrency in the process.

^ Correction: the J-turn intersection is between Route B, Route P, and U.S. Route 63.

The way I implemented the J-turn is to add link roads (separated by islands, so these link roads are justified) to the route relations.

Also added the J-turn intersection between Route A, Route P, and U.S. Route 63.

This also fixes the concurrency between Route A and Route B which ignored A entirely.

Regarding the concurrency, it does not span the two counties. It is entirely within Harrison County, but Route M is a long east-west route that spans the two.

Also fixed a TIGER error on nearby YY.

I verified all north/south roles in the relation.

This looks like an editing mistake where someone forgot to deselect a node when merging? Hard to say

The one number I corrected was on way #18627830. It had "name_2" tag claiming it was a continuation of PCR 616. I verified on Bing StreetSide (which remarkably has coverage here) that it's actually PCR 622.

Notice: The accuracy of these expanded names is 100% dependent on the accuracy of the original Pcr-initialism names. I did not reference any sources beyond imagery (to correct one incorrect road, which I'll mention next) to verify numbering.

I chose to use the "PCR X" form as the ref value for the ways. I think CR is more common nationwide, but PCR is more locally-appropriate. This is easy enough to change in the future. Similarly, I believe this is only an incremental improvement.

I should note that I couldn't determine whether PCR expands to "Perry County Road" or "Perry County Route", but picking one was a better thing than leaving abbreviations in the database.

Most of these roads had names of the format "Pcr X" where X is an integer. The "cr" letters were lowercase. These were carried over from the TIGER import.