Manhattan Project censored mail, November 24, 1944
Manhattan Project National Historical Park, New Mexico
General Leslie Groves, physicist Dr. J. Robert Oppenheimer, and more than 6,000 other personnel who developed the atomic bomb at Los Alamos National Laboratory in New Mexico once sent and received their mail from several undercover addresses, including PO Box 1663 in nearby Santa Fe. LANL became part of Manhattan Project National Historical Park in 2015.
National Postal Museum