North Dakota is the nation's fastest-growing state fueled by the oil boom in the western part of the state that is drawing workers seeking to cash in on the prosperity. The USGS updated its estimate of recoverable oil in the Williston basin to 7.4 billion barrels. The April 2008 estimate was 3.65 billion barrels. Shale plays are geographic areas where companies are actively looking for natural gas, and shale oil reserves in shale rock. This map shows the shale plays in the United States. NORTH DAKOTA QUICK FACTS • Unemployment rate in March was 3.3 percent, compared to the nation's 7.6 percent. • Population grew 2.2 percent to 699,628 in the year ending July 1. • Williston’s taxable sales and purchases for the third quarter of 2012 were $953 million compared to the much larger city of Fargo’s $712 million.