PARSONS, Kan. - An unlikely pilgrimage is under way to Dwayne’s Photo, a small family business that has through luck and persistence become the last processor in the world of Kodachrome, the first successful color film and still the most beloved.

That celebrated 75-year run from mainstream to niche photography is scheduled to come to an end on Thursday when the last processing machine is shut down here to be sold for scrap.

In the last weeks, dozens of visitors and thousands of overnight packages have raced here, transforming this small prairie-bound city not far from the Oklahoma border for a brief time into a center of nostalgia for the days when photographs appeared not in the sterile frame of a computer screen or in a pack of flimsy prints from the local drugstore but in the warm glow of a projector pulling an image from a carousel of vivid slides.

In the span of minutes this week, two such visitors arrived. The first was a railroad worker who had driven from Arkansas to pick up 1,580 rolls of film that he had just paid $15,798 to develop. The second was an artist who had driven directly here after flying from London to […]