Jeffery Nichols, If you haven't already seen it, please check out the Timezone Boundary Builder project here: https://github.com/evansiroky/timezone-boundary-builder. I have made a script that extracts data from OpenStreetMap to create shapefiles of the world's timezone boundaries. I'd be very interested in using some of your research and OpenStreetMap edits to produce better data. Evan On Tuesday, 14 January 2020, 06:19:49 pm PST, Jeffery Nichols <jeffery.nichols@gmail.com> wrote: Great! I was also wondering whether anyone on your team has more data about what towns were part of America/Nipigon. I'm trying to map all of the Canadian IANA zones on OpenStreetMap. Your tzdb mentions that Nipigon was the largest town in its zone, which suggests that the zone wasn't limited to Nipigon town boundaries, but it doesn't give any clues about what other towns were found to follow it. Thanks in advance. On Fri, 10 Jan 2020 at 16:51, Paul Eggert <eggert@cs.ucla.edu> wrote: Thank you for those corrections. I installed the attached patch to tzdb's development version and these fixes should appear in the next release. -- Jeffery Nichols, JD, MPA, MA