Sunday Stamps | USA 2018 Monochromes

Some classical designs for today's theme in Sunday Stamps: Monochrome.

These stamps were issued on 27 June 2018, along with a $5 one in brick red colour. They feature an illustration of the statue that tops the U.S. Capitol dome. The artwork is based on an engraved vignette originally created for a 1923 stamp, the $5 Head of Freedom Statue, by John Eissler (1873-1962). 

You can read more information about these stamps here. Also, I found a picture of the 1923 stamp (which I do not own):

Also in 2018, two stamps were issued in order to commemorate the centenary of the first air mail flight: on May 15, 1918, in the midst of World War I, a small group of Army pilots delivered mail along a route that linked Washington, Philadelphia, and New York—initiating the world's first regularly scheduled airmail service. (More information here).

The stamps feature a drawing of the type of plane typically used in the early days of airmail, a Curtiss JN4H biplane. This type of biplane was also featured on the 24 cent stamp that was issued in 1918 to commemorate the beginning of regularly scheduled airmail service. “EST” is an abbreviation for “established”. You can see the picture below (again, I do not own this).