[1] After Harvard Law, he joined the New York Central Railroad, the centerpiece of his family's vast railway empire, of which his father was president.

Following the death of his brother William in 1944, he remained the only active representative of the Vanderbilt family involved with the New York Central Railroad.

He served as a director and member of the executive committee until 1954, when the New York Central was subjected to a hostile takeover by business tycoon Robert R.

The British competitor for the 1914 America's Cup, Shamrock IV, was crossing the Atlantic with the steam yacht Erin, destined for Bermuda, when Britain declared war on Germany on August 5, 1914.

As the commodore of the New York Yacht Club, Vanderbilt sent the Vagrant from Rhode Island to Bermuda to meet the Shamrock IV and Erin, and to escort them to the US.

Having no radio, the crew were unaware of the declaration of war and finding all of the buoys and other navigational markers missing, they attempted to pick their own way in through the Narrows, the channel that threads through the barrier reef.

While at Block Island, one of his subordinates was Chief Machinist Mate Harold June who would go on to serve as a pilot with Commander (later admiral) Richard E. Byrd's 1929 Antarctic Expedition.

On July 17, 1918, he was reassigned to the US Navy forces in Europe and reported to Submarine Chaser Detachment 3 at Queenstown, Ireland, in August.

[3] As a boy, Harold Vanderbilt spent part of his summers at the Vanderbilt mansions—the Idle Hour estate in Long Island, New York, on the banks of the Connetquot River; Marble House at Newport, Rhode Island; and later at Belcourt, the Newport mansion of his stepfather, Oliver Belmont.

In 1934 Harold faced a dangerous challenger from the United Kingdom, Endeavour, owned by the aviation pioneer and industrialist Thomas Sopwith.

"[5] In 1936, Vanderbilt, with assistance from the other three had developed an alternative set of rules, printed them, and mailed a copy to every yachtsman that he knew personally or by name in both the United States and England.

Vanderbilt continued to work with the various committees of the North American Yacht Racing Union until finally in 1960 the International Yacht Racing Union (predecessor to the International Sailing Federation or ISAF) adopted the rules that Vanderbilt and the Americans had developed over the previous quarter century.

[16] In 1934, his sister, Consuelo Vanderbilt Balsan, built her own mansion on Hypoluxo Island, across the water from Eastover.

At the outbreak of the Second World War, Vanderbilt's yachts Vagrant and Vara, which was under construction, were seized by the United States Navy.

Navy official Edmond J. Moran met with Vanderbilt in New York, to present him with a check for $300,000 as compensation for the Vara.

He and his wife are interred at Saint Mary's Episcopal Cemetery in Portsmouth, Rhode Island, their graves marked with only simple flat stones.

[20] He helped guide the institution through a time in history when racial integration of the student body was a divisive and explosive issue.

[20][22] In 1947, Vanderbilt was invested as an honorary Commander of the Order of the British Empire (CBE) by King George VI.

Their bid was successful, and the property was converted into a museum that has been open to the public since the mid-1960s and holds documents and artifacts related to his life.

[23] Vanderbilt's private railroad car, New York Central 3, was renovated and has operated luxury charter trips at the rear of regularly-scheduled Amtrak and Via Rail Canada trains.