Between April 1952 and February 1953, three separate bills were introduced in the House of Representatives that called for a circulating half dollar "in commemoration of the one hundred and fiftieth anniversary of the purchase of the Louisiana Territory from France by President Jefferson in 1803."
In the 82nd Congress (1952), the bill was introduced by Thomas Hale Boggs, Sr. (D-LA), in the 83rd Congress (1953) Boggs tried his bill again in January and his efforts were supported by a duplicate bill introduced by Thomas Bradford Curtis (R-MO) in February. Each of the three bills was referred to the House Committee on Banking and Currency.
The Louisiana Purchase was one of the most important land acquisitions in US history, effectively doubling the size of the young country. The US purchased the ~828,000 square mile area for $15 million - roughly $0.18 per square mile - from France; the deal was initiated on the US side by President Thomas Jefferson - on the French side by First Consul Napoleon Bonaparte (during his pre-Emperor days). France had gained the area via a treaty with Spain in 1800. In the years that followed its acquisition, the territory would gradually be divided into multiple smaller territories (e.g., the Territory of Dakota) and eventually would yield 15 US States (in whole or in part).
As the bills called for a circulation coin, they left the mintage and design to the discretion of the Secretary of the Treasury. As would be expected with a call for a circulation coin, the bills did not include any limitations regarding which Mint facilities could be engaged in the striking of the coins, nor was a sponsor named.
It appears that Congress did not have much interest in supplementing the Franklin Half Dollar (or any of the previous half dollars still in circulation) with a Louisiana Purchase half dollar as none of the bills was reported out by the Committee or considered on the House floor. Boggs' 1952 bill died with the adjournment of the 82nd Congress, and the Boggs and Curtis bills of 1953 suffered the same fate when the 83rd Congress closed.
Fifty years later, Congress approved legislation that created a series of circulating five-cent coins to commemorate the Louisiana Purchase and the subsequent exploration of it by Captains Meriwether Lewis and William Clark. The first coin of the four-coin "Westward Journey" series celebrated the Louisiana Purchase's bicentennial.
Here are a pair of Philatelic-Numismatic Covers (PNCs), one with Philadelphia Mint coin, one with Denver coin - plus Info Card - for the 2004 Louisiana Purchase five-cent coin that was part of the "Westward Journey" series.



For more on the full "Westward Journey" series, check out:
2004-05 Westward Journey Nickels