Well, that's a great question with an economic answer. With the price of oil being what it is, expanding production is not profitable right now. Production is capital-intensive and requires a lot of money up front. Projected revenue has to be high as a result, and the money just isn't there right now.

OPEC is partially responsible for the low price of oil. Because they have such market power, if the price of oil starts getting too high, they flood the market with supply which drives down prices and drives out the marginal producers.

With the market set up the way it is currently, they can do that. For this to stop, we'd have to introduce political action restricting supply into the US from those areas using an import quota or some other tool. No politician will do this because in the short run, gas prices will rise, and they'll never get re elected. Eventually, the price would go back down as domestic production scaled up, but it would be a bumpy ride in the meantime.

Give me 30 minutes and I'll source all that. Can't do it on my phone.