Moving the A-12 Blackbird
This
is one you'll want to keep in your aviation archives because it's
exceptionally interesting and heretofore, a virtually unknown story.
It gives you a small clue to how expensive just one phase of the program was and the measures taken to maintain its secrecy.
The secret convey that moved the A-12 (Pre SR71 Blackbird) from Burbank, CA to Area 51 for flight testing.