This is actually very very bad for the U.S. The entire market, especially the S&P 500, is heavily invested/composed of Oil/Energy companies. Low oil prices spell disaster for these companies, especially those who assumed that oil would eventually come back up and level out around $50 a barrel. The market will continue to suffer until it can adjust to the idea that oil prices are going to remain low.
http://www.business-standard.com/ar...bad-for-financial-markets-115120900133_1.html
The impact is very negative for workers offshore and in the oil patch in Louisiana, Texas, North Dakota etc. These were relatively high paying jobs and there's no telling if/when they'll be back. The offshore guys typically work two weeks on and then get two weeks off. What do you think they did during those two weeks? Relatedly this is horrible news for hotels, restaurants and - ahem - other establishments in places like NOLA.