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.
Map & Directions. Aptly named Little Mountain is easily accessible year-round. This 522-acre forested parkâjust a few miles from Mount Vernonâs downtown areaâfeels much farther from the city. A narrow road leads to the sub-1,000-foot summit, where Skagit Valley views await.