Boundary disputes between states have historically been adjudicated in the Supreme Court of the United States. But it is unlikely that GIS maps have made much of an impact on a case until New Jersey and New York slugged it out in the nation's top court for Ellis Island in 1998. Ellis Island is a significant historical site because it was here that millions of immigrants first put foot in America. But where is Ellis Island? This paper will focus on how the New Jersey Department of Environmental Protection used GIS technology to assist the State's attorney general prepare the case as well as implement the Supreme Court's decision.