I've been working just a little on how to integrate
OpenStreetMap and
OpenHistoricalMap depictions of historic race tracks; here is a test case of the second Watkins Glen circuit overlaid on the current (fourth) Watkins Glen International. Use the sliders to change the emphasis. Need to do something about the colors; I want better contrast between historic and current.
http://www.na-motorsports.com/test/test.html