USPS introduces airmail

may 15, 1918

airmail has the obvious effect of making mail more timely, and timeliness is an important part of the relevance of the political pamphlet.

"Significant Dates." United States Postal Service. Accessed December 16, 2015. https://about.usps.com/who-we-are/postal-history/significant-dates.htm.

"Air Mail." Digital image. Antique Air Field. Accessed December 09, 2015. http://www.antiqueairfield.com.