Long Island is an island located in southeastern New York, United States, just east of Manhattan. Stretching northeast into the Atlantic Ocean, Long Island contains four counties, two of which are boroughs (Queens and Brooklyn) of New York City, and two of which (Nassau and Suffolk) are mainly suburban. In popular usage, however, the term ?Long Island? generally refers only to Nassau and Suffolk counties in order to differentiate them from New York City. The counties of Nassau and Suffolk have been long renowned for their affluence. From about 1930 to about 1990, Long Island was considered one of the aviation centers of the United States, with companies such as Grumman Aircraft, Republic, Fairchild, and Curtiss having their headquarters and factories on Long Island. Long Island has played a prominent role in scientific research and in engineering. It is the home of the Brookhaven National Laboratory in nuclear physics and Department of Energy research.