The datum is defined by the observed heights of mean sea level at the 26 tide gauges and by the set of elevations of all bench marks resulting from the adjustment. A total of 106,724 kilometers of leveling was involved, constituting 246 closed circuits and 25 circuits at sea level.
George Washingtonâs Mount Vernon is located roughly 15 miles south of Washington, D.C. and 8 miles south of Alexandria, Virginia on the banks of the Potomac River, at the southern end of the George Washington Memorial Parkway.
Mount Vernon is a neighborhood located just to the north of downtown Baltimore, Maryland. Designated a National Landmark Historic District and a city Cultural District, it is one of the city's oldest neighborhoods and originally was home to the city's most wealthy and fashionable families.