The 1936 (1938) Landing of the Swedes in Delaware Tercentenary Half Dollar came about via Joint Resolution in the US Congress, approved in 1936 (74th Congress). The House Joint Resolution for the coin was introduced by John George Stewart (R-DE) in March 1936, and the Senate Joint Resolution - the Resolution that was ultimately approved - was introduced by Joseph E. Guffey (D-PA) and Daniel Oren Hastings (R-DE) as a companion piece of legislation in the same month.
I would be remiss, however, if I didn't also shine the spotlight on Frank R. Zebley , a Delaware State Representative from Wilmington, Delaware. The local Zebley was reported to be a coin collector who included an example of every US commemorative half dollar - issued to that point - in his collection.
Zebley was a strong advocate for the Delaware coin, and was responsible for adding a Section to Delaware's State Senate Joint Resolution that created the Delaware Swedish Tercentenary Commission which, in turn, kicked things off for the coin.
Here's Zebley's coin-related contribution to the Joint Resolution:
Section 3. That the said Commission be and it is hereby authorized to request and direct the Senators and Representatives of the State of Delaware in the United States Congress to urge and prepare proper legislation in order to enable the United States Director of the United States Mint to prepare and have minted United States Half Dollars suitably commemorating the anniversary. The number of such commemorative half dollars to be limited to twenty thousand in number, and the sale price to be set at $1.50 each. The profit from such sale shall be used at the discretion of the said Commission in defraying the expenses incidental to the celebration, and the remainder, if any, shall be paid into the General Fund of the Historical Society of Delaware.The Resolution was approved on March 10, 1935 and paved the way for legislation to be introduced in the US Congress for the coin's minting. It is important to note, the Resolution included a provision that required the Commission to issue a report to the Delaware General Assembly in 1937 that included "recommendations for future legislation by the General Assembly."
This provision was fulfilled in January 1937, with the Report resulting in a new Resolution being passed by the General Assembly. The new Resolution replaced the Delaware Swedish Tercentenary Commission with the Delaware Tercentenary Commission and called upon the new Commission continue the work of its predecessor and to:
prepare plans and to carry out and execute said plans for a fitting celebration, in the year 1938, by the State of Delaware of the three-hundredth anniversary of the founding by the Swedes, in the year 1638, of the first permanent civilized settlement in the territory of the present State of Delaware and in the entire Delaware River Valley, at Fort Christina, near "The Rocks" on the Christiana River, and, to that end, to co-operate with other State Commissions, the National Commission, and the Commission appointed by the Government of the Kingdom of Sweden, also with all other commissions, committees, organizations and individuals having a similar purpose.It also transferred responsibility for the commemorative half dollar to the new Commission:
Section 4. That said Commission [Delaware Tercentenary Commission] be and is hereby further authorized to take over from the present Delaware Swedish Tercentenary Commission all rights and powers granted to it by joint resolution of the Congress of the United States authorizing the coinage of a half-dollar commemorating this tercentenary and to receive from said last named commission all moneys hitherto received by it from the subscribers and purchasers of said coins, less any portions of said receipts hitherto paid out by said last named commission on account of necessary expenses incurred by it in the discharge of its duties, and to continue to sell said commemorative coins and to use the entire proceeds thereof in its discretion to meet, as far as possible, the expenses of the proposed celebration in any and all of its aspects.The Delaware commemorative coin's Joint Resolution introduced in the US Congress in March 1936 was signed into law by President Franklin Delano Roosevelt on May 15, 1936. As this was before the creation of the Delaware Tercentenary Commission, the Public Resolution authorizing the half dollar lists the former Tercentenary Commission - the Delaware Swedish Tercentenary Commission - as the coin's sponsor.
With that, the Delaware Tercentenary Commission was authorized to manage the coin's promotion and sales and complete its assigned responsibilities.
1936 (1938) Landing of the Swedes in Delaware Tercentenary Half Dollar

For other of my posts about commemorative coins and medals, including more Delaware stories, see:
Commems Collection.