The story of Prince George's County begins in the sixteenth and seventeenth centuries—long before Maryland was ever established—with the discovery and exploration of the Chesapeake Bay and subsequent sailing up the Potomac River. Although the Spanish in the Caribbean knew of the bay, the English were the first to explore and chart it. What they found pleased them. Wrote Captain John Smith, the bay's first explorer, "Within is a country that may have the prerogative over the most places known, for large and pleasant navigable rivers, heaven and earth never agreed better to frame a place for man's habitation…. Here are mountaines, tails, plaines, valleyes, rivers, and brookes, all running more pleasantly into a faire bay, compassed but for the mouth, with fruitful and delightsome land."
Located in the state of Maryland, Prince George's County is directly adjacent to Washington, DC. It was established by the 1695 Maryland General Assembly to be effective on St. George's Day, April 23, 1696, from parts of Calvert and Charles Counties. It was named for Prince George of Denmark, husband of England's Queen Anne.
In 1748, a portion of Prince George's County was allocated to form Frederick County. Frederick County was subsequently divided to form what are currently Allegany, Garrett, Montgomery, and Washington counties. In 1791, a portion of Prince George's County was ceded to form the District of Columbia, Washington, DC. The county seat is Upper Marlboro, MD. The county is part of the Baltimore-Washington Metropolitan corridor.(Source)