Short answer:
Legitimate postal cancel from an open office, although at this point (and from only an envelope piece) it is impossible to tell whether this was a pre-dated early release or a clerk error. Being from a very small office about to be converted from 3rd class status to a rural branch, I would lean heavily toward this being a dating error.
Longer answer going into the weeds:
When I am generally curious about the dates of operation of a U.S. post office, I typically first go to the "U.S. Post Offices List" list on Jim Forte's website:
https://www.postalhistory.com/index.htmForte's list notes: Pantex, Carson County, Texas 1945-1969, (and is silent on the Rural Branch dates afterwards, see more below.)
If a year-date is not specific enough for me, then I go to original sources, in this case the "Postal Bulletin" to get the information directly from a
primary source.
Forte's list and the previous posts here built a good roadmap. I was intrigued by an unposted sentence in the link rogdcam supplied above:
Quote:
A post office was established in November 1944 for the plant employees who lived in government housing nearby.
Interesting, since it is not corroborated by the Postal Bulletins, that I can find. Perhaps only a company's convenience desk and not anything actually sanctioned by the USPOD. Because ...
Postal Bulletin 18784, dated December 29, 1944, page 2: Notes the establishment of Pantex (a Pantex village), midway between Amarillo and Panhandle, TX, to be supplied by Star Route yet to be assigned a route number. I see no actual notice of the establishment of that star route to create Pantex's effective "opening date", but it was apparently in early 1945.
Postal Bulletin 18825, dated May 22, 1945: Pantex changed "from fourth class at $72 to third class at $1900 effective as of Apr 1, 1945."
Pantex continued along as a third class office until 1969, when...
Postal Bulletin 20702, dated May 29, 1969, page 7: Pantex relegated from 3rd class to 4th class.
Postal Bulletin 20705, dated, June 12, 1969, page 5: Class-change order rescinded and Pantex instead made a rural branch of Amarillo effective June 12.
The quote posted by rogdcam has curious phrasing, no doubt written by a non-collector!
Quote:
The post office remained in operation until 1969, when it became a rural branch of the Amarillo post office.
To nitpick, it could have been better phrased as "The Pantex post office transitioned from a third class office to a Rural Branch of Amarillo in 1969 (and continued to serve patrons until it finally closed in 1980)". The average patron would not notice behind-the-scenes classification changes.
Postal Bulletin 21269, dated October 30, 1980, page 13: Pantex, then with a status of "CPO" (Contract Post Office) is closed and the CPO and Zip Code discontinued.