I think it's a case of the grass is always greener. I see a lot of great machines on shopgoodwill that are in the midwest.
A lot of pioneer women did bring their machines with them. In that time you would have too when any sort of amenities would have been few and far between compared to the eastern half of the continent. That's probably not the source of most of them though. After the railroads were built it was relatively easy to ship things, most things here are from after that timeframe. Truly old stuff tends to be much more rare.
Rodney