The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.By Nathan Slaughter NEW YORK ( StreetAuthority) -- With all the changes to the United States' energy landscape recently, it's easy to overlook one of the country's most important petroleum-producing regions: the Gulf of Mexico. For energy investors, drilling in the Gulf is hardly a new story. U.S. oil companies have been producing in this part of the country for years. Out of the 5 million barrels of crude the U.S. brings to the surface each day, 33% -- or 1.5 million barrels -- comes from this petroleum-rich region. But if you think this means we're done seeing growth in the Gulf, then you're sorely mistaken. According to the U.S. Department of the Interior (DOI), the Gulf of Mexico is home to roughly 75% of the nation's undiscovered offshore resources -- the bulk of which has been off limits to U.S. oil companies for years. But starting June 20, 2012, that's all about to change.