21¢ Prexie Solo - Unusual Usage

I picked up some interesting covers at Chicagopex this weekend. I am new to collecting prexie covers and am curious about this one. It is a 1956 domestic 4th class insured cover with a single 21¢ on it. I do not know what the 4th class rate was, nor do I understand how insured mail was priced.

Figuring out the usages on these covers is tricky. . .the lists of usages I see don't break out the components so you can easily figure out something that does not fir neatly.

I appreciate any help!

With this thread and your other Prexie thread just posted, the best advice is to pick up a copy of the Beecher-Wawrukiewicz "U.S. Domestic Postal Rates" book and dig in!

Thanks - I have a copy on the way!

I'm not sure it helps much, but this appears to be the envelope for a US Mint Set from 1955, and fourth class was the commonly used rate based on others I've seen at coin shows and online auctions.

A single combination of the coins for a year-mint weights about 1.04 ounces, and these would typically be in a cardboard holder so perhaps 2.0 ounces total per mint, and it appears all three mints (Philadelphia, Denver and San Francisco) were inside. My guess is about 6 ounces total, though I am likely off a bit.

And thank you, John Becker, for the reference to Beecher-Wawrukiewicz. I have a copy on the way for myself as well!

Then to answer your question more directly (and thanks to w0x0f for the very helpful information!), I get:

0.15 insurance fee based on US Mint's issue price for the 1955 P-D-S uncirculated mint set of 3.57 each, x3 = 10.71 total cost (thanks to the RedBook obtained at StampShow 2021 when the coin folks were meeting next door), and insurance for 10.01 -25.00 of coverage being 0.15 (from the insurance chapter in the B-W book).

0.6 postage, for 6 ounces of single-piece 3rd class postage at 1 cent per ounce for items over 2 ounces, from the W-B book. Even though the envelope is marked 4th class, it is really a case where merchanside less than 1 pound is rated as 3rd class, and when over 1 pound as 4th class (what many would traditionally call "parcel post").

0.21 total

Philazilla, with no disrespect meant for the books before or after, the 1994 book The Prexies by Roland E. Rustad is the 1938 Presidential Issue bible. Specifically it remains the bible because it listing the rating combinations available for each of the denominations of the stamps issued from $0.005 to $5.00.

The third edition of Tony's domestic rate book covers the domestic rates as well as a summary of international rates to foreign destinations. The prior editions do not have international rate information.There is a first edition of the foreign rates book also by Tony which can be found on line or with philatelic literature dealers.

That said, Prexies are an extremely popular and interesting series for postal history.

If you are really bitten by the bug, check out this source: https://www.usstamps.org/resources/prexie-era/ for the complete run of the Prexie Era Newsletter with articles about all things Prexie as well as other issues during the "Prexie Era."

Edit: Spelling and additional details.

Firstw0x0f

Ignoring what came before, beginning 4-15-1925 third class and forth class (Parcel Post) was divided by weight for merchandise. At first at over under 8 ounces then raised to 16 ounces. The term merchandise allowed for both 3rd and 4th class usages and an envelope label as 4th class was understood as third class matter (and postage rates) if below the parcel post (4th class) weight minimum.

See: https://goscf.com/t/88304#816621 for a more detailed list of Prexie resources provided to the OP in his companion Prexie thread..

In my post immediately above,
should have read, "At first at not over under 8 ounces...."

Thank you all - and welcome w0x0f!