It turns out that Peoria is not just a metaphor, but a real place in Illinois. It is also the location of a rather messy GIS import of County data! Here’s the history as far as I can determine:

• The Peoria County Government gathered data resulting in a dataset as of 1997.
• In 2010, that dataset was considered old enough to be considered “obsolete” which apparently justified uploading it to OSM.
• A wiki page Peoriagisuploa describes most of the details of what happened in June 2010. Basically, it’s woods and buildings.
• Woods came in with natural=wood (but too many nodes)
• Buildings came in with building=yes and BUILDING_T=(0..9) for a building type, as documented on the wiki page.
• In July 2010, user account “xybot” applied some changes called “Correction of faulty peoria bulk upload” which did a very strange thing to the building tags. It changed “BUILDING_T” to “tiger:buildingType” (!) There is no such tag in TIGER (which has no buildings, let alone building types).

I studied this mess and figured out what should have occurred: mapping Peoria’s BUILDING_T onto the actual, standard OSM building types:

• BUILDING_T=1 -> building=residential
• BUILDING_T=2 -> building=commercial (very few of these are industrial)
• BUILDING_T=3 -> building=school
• BUILDING_T=4 -> building=garage
• BUILDING_T=5 -> building=static_caravan
• BUILDING_T=6 -> building=industrial (there are almost none of these)
• BUILDING_T=7 -> building=yes (it was under construction in 1997, it isn’t now)
• BUILDING_T=8 -> (make these the inner ways of multipolygon relations)
• BUILDING_T=9 -> man_made=pier

I have been laboriously applying these fixes recently, and will finish soon. I’m doing it manually in JOSM, checking carefully, not only because that’s the quality thing to do, but also to head off any claims of “mechanical editing”. I’m also cleaning up the woods, which is not simply a matter of decimation but also a lot of manual updating because the woods are not where they were in 1997.