The Oxford Project

In 1984, photographer Peter Feldstein set out to photograph every single resident of his town, Oxford, Iowa (pop. 676). He converted an abandoned storefront on Main Street into a makeshift studio and posted fliers inviting people to stop by. At first they trickled in slowly, but in the end, nearly all of Oxford stood before Feldstein’s lens. Oxford Project link.
The CBS "Sunday Morning" video segment about Peter Feldstein's Oxford Project. Link to video.