As of the beginning of 2007, the United States has an estimated 20.97 billion barrels of crude oil listed as proven oil reserves. At the beginning of 2006, the United States stood at 21.72 billion. So, in one year the decrease in proven oil reserves was about 3.6%.

Of the fifty states in the country, thirty one states have oil reserves. The top five states are Texas, with an estimated 4.9 billion barrels; Alaska, with 3.9 billion; California, with 3.4 billion; Wyoming, with 0.706 billion; and New Mexico, with 0.696 billion. [Baltimore Sun]

In addition to these numbers, large amounts of crude oil reserves are located in federal offshore fields, primarily in the Gulf of Mexico. About 3.7 billion barrels are estimated to be in the Gulf area. In addition, it is estimated that about 0.441 billion barrels are located off the western coast of the United States, in federal fields of the Pacific Ocean.

According to CNNMoney.com, about 80 million offshore acres are leased by various oil producing companies. However, over 70 million offshore acres are not leased and are not producing oil. [CNNMoney.com: “America's untapped oil”]

The U.S. Geological Survey (USGS) released a report in April 2008 that suggested the Bakken Formation in Montana and North Dakota could produce between 3.0 and 4.3 billion barrels of recoverable oil in its field of approximately 200,000 square miles (520,000 square kilometers). This oil is not among the proven oil reserves now counted for the United States.

Land in the Arctic National Wildlife Refuge, in Alaska, has also been considered for recoverable oil. Such oil could amount to between 5.7 and 16.0 billion barrels.

In addition, the United States contains the largest known deposits of oil shale in the world. The U.S. Bureau of Land Management (BLM) estimates that 2,500 billion barrels (2.5 trillion barrels) of potentially recoverable oil is available. Such an amount, under current usage rates, would last for over one hundred years. Since oil shale reserves is not a commercially viable venture, as of yet, they are not included within the U.S. proven oil reserves.

The top 15 proven oil reserve countries in the world are listed on the next page. Please read on.