The aerial photography of the USGS (mentioned earlier as the "pick
location on a map for photos" reply) is one of the best sources of
aerial photos from 1930 through present day. Coverage varies, but I was
able to find photography of the area in Wisconsin I model from 1938,
1951, 1954, 1960, 1975 and into the 80's.

http://edc.usgs.gov/products/aerial.html click on "Photo Reference
Mosaics" or go straight to "Earth Explorer", where you can enter a
location and find all the imagery held by USGS for that location. But
be advised, not all the imagery comes up on that search. Neither the
1951 nor 1954 imagery for my area came up, but after I got in touch
with the staff, they found it for me.

The staff at USGS is very helpful, and can guide you through. Prices
can be steep, but the photography is excellent. I was able to count
individual ties in the track from the 1954 photos.

Regards,
Andy Laurent