Chicago, Ill., Tube Station Pneumatic Mail, 1908-10. 7 post cards and cover; with "Chicago, Ill., N. Western Tube Sta." duplex transit postmarks and one with "Last Mail Tube Sta." duplex postmark, nice range of usages including incoming and out of state, origin state and out of state (Pueblo Colo.), local, transit (Me. to Wis.) and cover a forwarding usage (2¢ faulty), F.-V.F. overall. Estimate  $300 - 400. $0 (Image)