One of a Kind Postal Keepsakes

My father, Loius H Linneweh, worked at the Elmhurst, IL, post office from Oct. 1945, (when discharged from the US Army), till Oct. 1973. Most of his career he was "Lou, at the window", handling the public and corprate customers who walked in. Durring this time Dad collected stamps, plate blocks, canceled first issue stamps, post cards, sent envelopes, etc. Here are just a few of the interesting postal items he had.
Pic.#1, [top pic, front], is a first flight, U.S.AIR MAIL, CHICAGO AREA, EXPERIMENTAL HELICOPTER SERVICE, OPERATED BY ARMY AIR FORCES. This envelope was mailed in a cover envelope to a clerk in the Chicago Office. The clerk then sent it via "Air Mail". It's post marked, Oct. 1, 1:00pm, 1946 AMF, (Air Mail Field), Chicago, Ill. The back, [bottom pic], shows it was recived in Elmhusrt, Ill, Oct. 1, 2:30pm. All for 5 cents.
Pic.#2, is an envelope sent from Villa Park, Ill, Via Pony Express, to my Father, Monday Aug. 22, 9AM, 1949. Frank Breycha, Postmaster. The Pony Express ran that day from Villa Park to Chicago, as a community event for the village's 35th year. This envelope was recived in Chicago, [lower pic, back], Aug. 22, 3pm, 1949. My Dad got it from Chicago via regular mail.
Pic.#3, [top], UNITED STATES AIS MAIL SERVICE VIA Helicopter, FIRST FLIGHT, AM, CHICAGO AREA. This envelope was mailed from Elmhurst, post marked, Oct. 24, 3PM, 1949. It went to the Elmhurst Air Field, flew to Chicago Post Office, recived [bottom pic, back], OCT 24 5PM, 1949, AMF, then came back through regular mail.
Pic.#4, This envelope was sent in a cover envelope to a clerk in New York City Post Office. It was then mailed, post mark is JUL 3, 6 AM, 1952. [top pic, front], via the S S United States, MAIDEN VOYAGE FROM NEW YORK, JULY...1952, TO HAVE - SOUTHAMPTON. [lower pic, back]. Post marks on the back show it was recived in Le Havre, (France), 12pm, 8-7,(July 8), 1952, PAQUEBOT, (French -ship mail). Recived back in Elmhurst, Jul 17, 1 pm, 1952. Quite a trip, and record setting too.
[From Wikipedia] On her maiden voyage on 4 July 1952, S S United States broke the transatlantic speed record held by Queen Mary for the previous 14 years by over 10 hours, making the maiden crossing from the Ambrose lightship at New York Harbor to Bishop Rock off Cornwall, UK in three days, 10 hours, 40 minutes at an average speed of 35.59 kn (40.96 mph; 65.91 km/h) The liner also broke the westbound crossing record by returning to America in three days 12 hours and 12 minutes at an average speed of 34.51 kn (39.71 mph; 63.91 km/h), thereby obtaining both the eastbound and westbound speed records and the Blue Riband—the first time a U.S. flagged ship had held the speed record since the SS Baltic claimed the prize 100 years earlier.
And this envelope made both trips, how cool.
Thanks for looking;
Lumpy