1971-D Penny No Mint Mark In A Mint Set

Lincoln cents that didn't have mint marks are from Philadelphia. Only the 2017 Shield Cents had a P mint mark. If the rest of the coins are from Denver, then it's probably a packaging error.

I do believe although I cannot confirm that coin sets put out by the government are packaged at a central location. It would make sense with all the different sets they put out rather than having equipment for it at every mint. After all, the government wouldn't waste our money would it?

Thanks to everyone for your comments. And the packaging error does make sense. BUT - please - someone out there please explain to me why this same, simple logic did not apply to the Great Collections auction 4 months ago that sold a no mint mark dime for half a million dollars!!! Here's the way I saw it - It was a 1975 dime in a proof set of 1976 mint marked coins. Wrong year and no "S" mint mark? Would that not add up to packaging error?

Because the missing S was a genuine error, not a packaging error.

The coin was MINTED without the mintmark because it was left off the die.

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I hate to dwell on this, but one last point. What am I missing that I can't wrap my head around this? If there is no mint mark, why do you still say it was a San Francisco minted dime? Why can't it be a Philly dime from 1975 (hence no mint mark) that was slipped in as a packaging error, if there is a central packing centre where coins of different mints are assembled and packaged as has been previously suggested? If it was a 1975 SF minted dime without a mint mark, why a whole year's date difference? It would have had to be a 1975 SF dime minted the whole year prior missing it's mint mark that somehow a year later was included into a 1976 proof set. I can accept missing it's mint mark, but totally different year productions also? What are the odds?

I think OP is referring to info I feel like I recall in the 60s part of 70s and part of early 80s maybe, Government put out sets that came in envelopes with both blue P coins and Red D coins, I had a few 70, 71, 72 sets. https://www.collectorsalliance.com/...t-p/4490.htm
Blue package p sets came with a Philadelphia business strike and a San Francisco business strike. https://www.collectorsalliance.com/...t-p/7260.htm
The Philadelphia Mint produced proof sets for the United States from 1936 to 1964. In 1968, the Philadelphia Mint stopped producing proof coins and they began to be produced in San Francisco https://www.usmint.gov/learn/collec...s/mint-marks


Now with that being said, I think OP is wondering how exactly was the process done? I've heard coins would be shipped then packaged at one location, but recently I have not found that to be answered at all on any Gov stuff. Everytime it's brought up, is about that it was done, and not how it was done.

Cheers