http://bkg5ofjslnbyqvu55sjonpdyp3wmfsgq23u7vpk3wxn7ewgdeocpgwid.onion?page=article&article=The+Historic+Use+of+Dead+Drops+in+Espionage+and+Spycraft.html
By the 20th century, during the Cold War, dead drops became a hallmark of espionage between rival powers, especially the United States and the Soviet Union. In an era of intense surveillance and counterintelligence, both sides developed elaborate techniques to create dead drop locations in urban and rural settings.