The collection consists of photographs taken during the first years of the United States Post Office Department air mail service. Many of these photographs are portraits of individual air mail service pilots. The first use of air mail in the United States occurred in September, 1911, while the first air mail route from Washington to New York via Philadelphia started in 1918. A transcontinental route was established by 1920. In 1925 the government transitioned out of the air mail business with the passage of the Kelly Air Mail Act, which called for commericial airlines to bid on air mail routes established by the Post Office.