[Untitled photo, possibly related to: Freight train operations on the Chicago and Northwestern Railroad between Chicago and… https://www.rawpixel.com/image/12291366/photo-image-sky-technology-public-domainFree Image from public domain licenseEnsenada, Puerto Rico. Sugar mill or "central" of the South Puerto Rico Sugar Company. Sourced from the Library of Congress. https://www.rawpixel.com/image/12280081/photo-image-sky-smoke-public-domainFree Image from public domain licenseAt the railroad terminal in Caribou, Maine. Sourced from the Library of Congress. https://www.rawpixel.com/image/12278304/photo-image-cloud-person-skyFree Image from public domain license