Railway Mail Service
The United States Postal Service's Railway Mail Service was a significant mail transportation service in the US during the from the mid-19th century until the mid-20th century. The RMS carried the vast majority of letters and packages mailed in the United States from the end of World War I until the 1960s.The last route run by a railway post office was between New York and Washington, D.C, and ended on June 30, 1977.