Tracking down reliable mintage figures for issues of the US classic commemorative coin series can sometimes present challenges as the numbers from different sources don't always match up.
For example, Howland Wood, in his
The Commemorative Coinage of the United States volume (published by the
American Numismatic Society in 1922), regarding the two types of Louisiana Purchase Exposition (LPE) gold dollar coins, reported that "Only about 35,000 of the 250,000 coins [struck] were sold and the remainder were destroyed about 1914." This 35,000 net mintage figure was repeated by multiple authors/researchers over the years, and continues to be used to the present day.
(Note: The Mint did not report the Jefferson type and McKinley type of the LPE coins separately.) Wood's number is based on US Mint Reports of the time which indicated 215,250 of the 250,250 coins struck were melted (leaving a net mintage of 35,000 for the two versions combined).
In contrast, the
Final Report of the Louisiana Purchase Exposition Commission (from 1906) reports that 33,588 coins were sold, not 35,000. It reported a premium of $67,176 earned on the coins - 33,588 X $2.00 (selling price was $3.00 vs. Commission's purchase price of $1.00 {face value} leaving a $2.00 premium). After deducting expenses of $13,506.67, a net premium of $53,669.33 ($67,176.00 - $13,506.67) was reported as earned on the coin sales. The Report states that the coin counts and sales results were audited and confirmed before being published.
The Commission's sales/distribution figure is 1,412 coins lower than the Mint-based net mintage figure of 35,000. What could be the cause of the difference?
IMO, it's possibly a combination of:

The coins that were given out as gifts/appreciation awards by the Exposition are included within "Expenses" vs. "Sales" as they did not generate revenue. The 200 specially-packaged proof coins given to Commission members and other VIPs would be one example of this "non-sale" coin distribution.

Farran Zerbe keeping some of the unsold coins "off the books" after the close of the Exposition for his later sale. Zerbe is known to have sold the coins during his later travels with his "Money of the World" exhibit and at his concession booth at future expositions. As the Manager of the Souvenir Coin Department of the Exposition, it seems within the realm of possibility that Zerbe held some coins back for his own use (with or without the direct permission of the Exposition Company).
Of course, the discrepancy could have been the result of something else entirely, but when the numbers from two reputable sources don't match up, it does bring up questions.
1903 Louisiana Purchase Exposition Gold DollarsThomas Jefferson Type
William McKinley Type
(Image Credit for both coins: PCGS CoinFacts.) For other of my posts about commemorative coins and medals, including more on the history of the Louisiana Purchase Exposition gold dollars, see:
Commems Collection.