From Burlington, Wisconsin that is. Some more late-night surfing for online tidbits of info on the old Fox River Valley RR led me across this gem of a discovery. Sweet... loads of details on the TM interurban line that ran between both cities - the grade I plan on using for my fictional UP (C&NW) Burlington subdivision.
A couple of pages stand out - here photos of the through girder bridge that carried the line over the White River in Burlington, as well as the diamond crossing with the Soo Line tracks (later WC-CN). Also a couple of pages later shows the orientation of the curve from the bridge onto Congress Street, which then curves towards the northeast to begin the private right-of-way alignment towards Rochester.
Looking over Google Maps the retaining wall in the second photo is still there, now edging the back of a used-car dealership's parking lot and along the Fox River. As is common with many former interurban ROW's a utility line marks the location of the old track alignment in this section. Scrolling to the right shows where the private ROW begins, now a rails-to-trails path.