In a strange sort of way, I once convinced myself that I was glad no New York Central Hudson had been preserved: they personified the steam era at its best, running freely on the main lines of one of the greatest railroads, pulling the most legendary of express trains: to live in "captivity" after that, to be a mere museum exhibit, would have been too shameful...
O.k., let's leave that thought aside.
What if an even-worse-than-WW II scrap metal drive meant that only three steam locomotives could be preserved in all of North America. What should they be?
Well, it would be nice if one could, when the emergency was over, be operated, could pull excursion trains. So this one should not be too heavy, shouldn't have too long a wheelbase (modern railroads don't want to risk track damage): so maybe a light pacific. One, for static preservation, should show visitors to the continent's only remaining steam museum just how gigantic big steam had been: a Big Boy or an Allegheny. And the third, maybe, should represent 19th century steam: a 4-4-0.
Not the collection I (as a deep-dyed rail enthusiast) would LIKE, but maybe the best for educating the people who have never before learned the history of railroading.