I have purchased a lot of women in aviation cachets on Ebay.
A cachet is an envelope that has been specially prepared to commemorate an event. A first day cover is a cachet that was issued on the day when a postage stamp is issued for the first time, usually with a ceremony at a location significant to the subject of the stamp.
Below are two cachets from the 1946 National Air Races. The one signed by Marge Hurlburt was cancelled on August 31, 1946 in Cleveland Ohio. As you’ll see below, the cachet signed by Helen Chappell was unstamped and uncancelled.
The National Air Races were founded in 1920 in a (successful) effort to popularize aviation, and consisted of cross-country air races and pylon air races. The first races, in 1920, were sponsored by Ralph Pulitzer, a newspaper publisher, and the son of Joseph Pulitzer, also a newspaper publisher who was the founder of the Pulitzer Prize.
Each of the first nine National Air Races were held at a different airport in a different state.
In 1929, the National Air Races took place in Cleveland, Ohio, and it was part of the publicity for that event that the first woman’s cross-country air race, with Amelia Earhart and Louise Thaden among the participants, took place.
In 1930 the National Air Races were held in Chicago, Illinois, then they were held for two years in Cleveland, then once in Los Angeles in 1933, then two more times in Cleveland, then again in Los Angeles, then from 1937 to 1939 back in Cleveland, Ohio.
The National Air Races were launched again after the end of World War II, and were held on August 31 – September 2, 1946.
Halle Trophy Race
There were many races at the National Air Races. The only one specifically for women was the Halle Trophy Race. It was named after its major sponsor, the Halle department store in Cleveland. Five women pilots participated in the race, with the winner being Marge Hurlburt. Jane Page came in second. Other participants were Helen Chappell, Dot Lemon and Arlene Davis.
The “closed” course for the Halle Trophy Race was five laps around a 15-mile course, for a total of 75 miles. The pilots were limited to modified versions of the North American T-6 Texan, a single-engine plane that had been used to train U.S. pilots during World War II.
Bibliography:
https://en.wikipedia.org/wiki/Halle_Trophy_Race
Richmond News Leader, Monday, August 26, 1946, page 15