In 1936, the US Mint struck a commemorative half dollar to help celebrate the opening of the San Francisco-Oakland Bay Bridge - the coin is commonly referred to as the "Bay Bridge." I've previously discussed the Congressional path taken by the coin and how the issued coin could have had a different focus/theme. (See link below.)
In February (House) and March (Senate) of 1937, companion bills were introduced that proposed to re-allocate a portion of the mintage specified in the original Bay Bridge legislation. The amendments sought to reduce the Bay Bridge's authorized mintage from 200,000 to 100,000 and to use the freed up 100,000 coins to strike new half dollars to help commemorate the opening of the Golden Gate Bridge in San Francisco; the Golden Gate Bridge opened about six months after the San Francisco-Oakland Bay Bridge (May 27, 1937 vs. November 12, 1936).
Upon its introduction, the House bill was referred to the House Committee on Coinage, Weights, and Measures; the Senate bill was referred to its Committee on Banking and Currency. The House bill was reported out favorably, with a few non-substantial amendments, but the Senate Committee remained silent.
The House accepted the recommendations made by its Committee - namely, strengthen the wording regarding the limit of coins being struck at only one Mint facility, and adding a provision to ensure that the Director of the Mint approves the bank selected to sell/distribute the coins. (The Bank of America was identified in the bill as the bank sponsor of record.) The Whole House passed the amended bill without debate.
The bill was then sent to the Senate for concurrence. Once received in the Senate, it was referred to the Committee on Banking and Currency. The Committee, however, took no action on the bill, preferring to keep the original, Senate-introduced, Bay Bridge Commemorative Coin Act in place unchanged. The House was powerless to move forward without the Senate's concurrence, so the bill died and no Golden Gate Bridge coins would be struck. The final net mintage for the Bay Bridge half dollar was 71,369; 28,000+ were returned to the Mint to be melted in 1937. There would have been plenty of coins to go around for both bridges had the Senate been a bit more flexible!
1936 San Francisco-Oakland Bay Bridge Half Dollar

For more on the designs and specifications of the issued Bay Bridge half dollar, see:
-
1936 San Francisco-Oakland Bay Bridge-
1936 San Francisco-Oakland Bay Bridge - Redux-
1936 San Francisco-Oakland Bay Bridge - Ephemera-
1936 San Francisco-Oakland Bay Bridge - Distant Cousin-
1936 San Francisco-Oakland Bay Bridge - Coins Depicting Places ThreadFor other of my posts about commemorative coins and medals, check out:
Commems Collection.