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Hello. Aperture cards are indeed very similar to microform or microfiche. The picture shown on the Wikipedia article that you linked to (Aperture card - Wikipedia ) gives an idea of what this media types looks like.
Presently, the Cartographic Branch does not have an aperture card reader. Aperture cards may be viewed on our microfilm readers. The Cartographic Research Room (Room 3050) has multiple readers available, including several Minolta Readers that can print. Print copies may be made from these readers at a charge of $0.40 per page (per card in this case). The Cartographic Research Room does not have any microfilm scanners. While it may be possible to have a small number of aperture cards transported to the Microfilm Reading Room to utilize their microfilm scanners, the easiest way to duplicate these records digitally, especially given the large number of aperture cards in this series, would be to photograph the microfilm reader screen to capture an image of the aperture card. See #ResearcherProTip: Microfilm Made Easy for tips about photography and microfilm readers.