Chicago, Illinois. Telegraph switch board of the Pennsylvania railroad in the Pennsylvania telegraph room at the Union… https://www.rawpixel.com/image/12337277/image-person-technology-public-domainFree Image from public domain licensePittsburgh (vicinity), Pennsylvania. Montour Number Four mine of the Pittsburgh Coal Company. Miners in the room where lamps… https://www.rawpixel.com/image/12337305/image-person-public-domain-hospitalFree Image from public domain licenseAt the control board of the teletype room. Municipal airport, Washington, D.C.. Sourced from the Library of Congress. https://www.rawpixel.com/image/12325456/image-person-technology-public-domainFree Image from public domain license[Untitled photo, possibly related to: Pittsburgh (vicinity), Pennsylvania. Montour Number Four mine of the Pittsburgh Coal… https://www.rawpixel.com/image/12291843/photo-image-person-public-domain-hospitalFree Image from public domain licenseWarehouse at fruit terminal. Chicago, Illinois. Sourced from the Library of Congress. https://www.rawpixel.com/image/12286150/photo-image-background-person-patternFree Image from public domain license