by Mike Stupar
Ohio Central Systems SD40-2 puzzle, based on an original photo by Mike Stupar (photo copyright Mike Stupar -- used with permission). Photographed at Columbus, Ohio, May 18, 2017.
The "Easy" version of the puzzle has about 100 pieces, "Medium" has about 200 pieces, "Hard" is about 300 pieces. For the Online puzzles, see the Online Puzzle Tips.