<p>A Pitcairn PA-5 Mailwing on display at the Smithsonian Air and Space Museum in Washington, D.C.
</p><p>The United States Post Office Department began flying mail by air in May 1918.  At first, the mail was carried by the U.S. Army Air Corps, but within three months the Post Office had purchased its own planes and established its own fleet of aircraft.  This lasted for nine years.  Air mail was extremely dangerous work, with 30 percent of the pilots dying in crashes.  At first, planes flew only in the daytime.  But night flying soon became common as ground beacons and lighted emergency landing fields were built.  Regular transcontinental air mail service began in 1924.
</p><p>In 1925, Congress passed the Contract Air Mail Act (better known as the Kelly Act).  This authorized the Post Office to use private contractors to carry the mail.  Contractor-carried mail begin moving in April 1926, and by 1927 nearly all U.S. air mail was being carried by private companies.
</p><p>The Pitcairn Aircraft Company was created in 1926 out of a flying school (which itself would later become Eastern Air Lines).  Deciding to get into the air mail business, the company decided to build a very rugged aircraft that would be very easy to fly.
</p><p>The Mailwing was constructed of chrome steel tubing, wooden spars, and plywood ribs covered with fabric.  The horizontal tail could be moved in flight, which was an innovative feature at the time.  Mail was carried in a fireproof compartment in front of the cockpit.
</p>
Mailwings flew the mail from 1927 until 1934, when dedicated air mail flights ended.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/23165290@N00">Tim Evanson</a> from Cleveland Heights, Ohio, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/timevanson/7276905878/">Pitcairn PA-5 Mailwing - Smithsonian Air and Space Museum - 2012-05-15</a>