My thanks to Sherri Greene Ottis for allowing me to reproduce the following map, “Major Escape Routes Through France, 1940-1945.” from her book, Silent Heroes, Downed Airmen and the French Underground, Lexington, Kentucky: The University Press of Kentucky, 2001. Although there were other escape routes, these certainly were some of the most important. To enlarge it and make it more readable, click once on the map and then once again.
A similar map was prepared by the National Museum of the US Air Force, which has kindly allowed me to reproduce it below. To enlarge it significantly and make it more readable, click once on the map and then click a second time.