Wink,
In terms of opossum, definitely a former southeastern states species but they have as you mention exploited well beyond that.
In northern climates and higher elevations we usually see as I'm sure you have that "grinners" can have ears and tails that suffer
frostbite and other damage from the cold they weren't built for.
They of course as we all know are very adapted to human developments and like skunk and raccoon tend to do even better in these areas due to human provided food and shelter.
That said I'm sure some folks have helped move them along. The average live trapper (homeowner) moves animals 10-15 miles in my experience and if you keep piggy backing that movement on top of natural expansion and a highly reproductive animal you spread things quicker..
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In terms of raccoon the only thing I would reach back to and blow the dust off is the aspects about what the landscape mostly related to large uncut tracts of forest land prior to European colonization would be the final stage of succession (old growth forests).
While these forests have amazing species and ecosystem benefits they generally hold less diversity in terms of food and support for animals like raccoon that thrive on edge habitat and early succession and mixed succession forest and field complexes like we enjoy more of today with mixed land use.
So while I can't say where raccoon were and weren't before we arrived so to speak, I do know species groups differ based on these succession phases and while the old growth is important to many, to put it plainly and non scientifically, it sucks for things like raccoon compared to others...
There's my submission....
I'd add we of course have moved and continue to move wildlife and often beyond natural dispersal distances for young of year.
It is the nature of our involvement with the urban and suburban species of the country.
