Finally the obvious story on this. But it is missing the treaty that US and Mexico signed to close the Western Gap- ratified in early 00's. But later US applied and was granted ‘Extended Continental Shelf'. This closed the Western Gap prob to the prior treaty line.

https://www.nytimes.com/interactive/2025/02/13/world/americas/gulf-mexico-trump.html?smid=nytcore-ios-share