Maryland is a state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia and the District of Columbia to the south and west, Pennsylvania to the north, and Delaware to the east. Historically it was part of the Chesapeake Colonies where planters cultivated tobacco as a cash crop dependent on slave labour.[5][6] It is comparable in size to the European country of Belgium.According to the U.S. Census Bureau, Maryland has the highest median household income of any state at $68,080 in 2007, overtaking New Jersey in 2006.------------------ It was the seventh state to ratify the United States Constitution and bears two nicknames, the Old Line State and the Free State. Its history as a border state has led it to exhibit characteristics of both the Northern and Southern regions of the United States. Generally, rural Western Maryland resembles West Virginia and Western Pennsylvania,[citation needed] the Southern and Eastern Shore regions of Maryland emulate a Southern culture,[8] while densely-populated Central Maryland—radiating outward from Baltimore and the Washington Beltway—exhibits characteristics of the Northeast. ---------------- Maryland is a life sciences hub with over 350 biotechnology firms, making it the third-largest such cluster in the nation. Institutions and agencies located throughout Maryland include the University System of Maryland, The Johns Hopkins University, Howard Hughes Medical Institute, Celera Genomics, Human Genome Sciences (HGS), the J. Craig Venter Institute (JCVI), the Food and Drug Administration (FDA), MedImmune (recently purchased by AstraZeneca), the National Institutes of Health (NIH), and the National Institute of Standards and Technology (NIST).