The largest sale of oil leases in the Gulf of Mexico in nearly 35 years is coming. AP reports, a proposal from the secretary of the interior would open the entire gulf to exploration. That's 73 million acres, the most since 1983. The most recent regional sale offered 48 million acres, with sparse bidding, only about 2%. Bidding is likely to be more robust on the heels of Exxon Mobil's announcement of $20 billion in planned Gulf projects.