Overnight photo labs in the US?

Hi folks,
this may be somewhat off topic but I hope not too far :-).
I will be on a trip through Colorado, Wyoming, Montana and South
Dakota in May and June.
While I will take photos mainly with my SLR-equipment, I plan to take
one pinhole camera on this trip. Did not decide yet, wether it will be
a 4x5" or one of my medium format Zero's.
The problem is, that I would like to see the pinhole images as soon as
possible to decide if I should do them again (due to the uncertainties
of the exposure of a pinhole image) before I head on to the next
place.
How is it in the mentioned area? Does one usually find one hour or
overnight photolabs in the (bigger) cities, that can do medium format
(maybe even large format) slide film or is there no chance? Are
chances better for negative film?

Thank you!
Dieter
 

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Dieters Lochkamera Seite: http://www.die-lochkamera.de/
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