Today, the tension between preservation and development is seen in the Arctic National Wildlife Refuge (ANWR) drilling controversy. The question of whether to allow drilling for oil in ANWR has been a political football for every sitting American president since Jimmy Carter. Studies performed by the US Geological Survey have shown that the "1002 area" of ANWR, located just east of Prudhoe Bay, contains large deposits of crude oil. Traditionally, Alaskan residents, trade unions, and business interests have supported drilling in the refuge, while environmental groups and many within the Democratic Party have traditionally opposed it. Among native Alaskan tribes, support is mixed. In the 1990s and first decade of the 21st century, votes about the status of the refuge occurred repeatedly in the U.S. House and Senate, but as of 2007 efforts to allow drilling have always been ultimately thwarted by filibusters, amendments, or vetoes.