A wealthy resident of Westbury,Long Island, New York, his father had been involved in the newspaper business with Charles Anderson Dana. In 1891, Thomas Hitchcock married Louise "Lulie" Eustis (c.1867-1934) of Washington, D.C., daughter of George Eustis and Louise Corcoran Eustis.George Eustis of New Orleans,the eldest son of George Eustis,formerly the Chief Justice of the State of Louisiana, had recently been appointed Secretary to John Slidell, the designated Confederate States Minister to France.They had two sons, Tommy Hitchcock, Jr. and Francis Center Eustis Hitchcock, and two daughters, Celestine Eustis Hitchcock, who married New York City architect Julian L. Peabody and died with him in the marine disaster, the sinking of the S.S. Mohawk off the coast of New Jersey in January of 1935, and Helen Hitchcock who married Averell Clark, also of New York City.
Thomas Hitchcock was a key figure in developing the sport of polo in the United States. In 1877 he and his friend August Belmont, Jr. were part of the group that organized the first ever polo match on Long Island, New York, played on the infield of the racetrack at the Mineola, New York, Fair Grounds . One of the first 10-goal players in the U.S., Hitchcock's efforts resulted in the 1881 formation of Long Island's [[Meadow Brook Club. In 1886 he was a member of the United States team in the first International Polo Match that played for the Westchester Cup. A polo player herself, and the founder in the year 1916 of the Aiken Preparatory School, Louise Eustis Hitchcock had her sons playing polo as soon as they were old enough to swing a mallet. She also helped family friend Cornelius Vanderbilt Whitney to learn the game. Son, Tommy Jr., would become a polo player who is considered by many expert observers as the greatest to have ever played the game.
Thomas Hitchcock and his wife spent virtually every winter at their 3,000 acre estate in Aiken, South Carolina]] where in 1892 he founded the Palmetto Golf Club. At that time, the city served as a winter playground for many of the country's wealthiest families such the Vanderbilts and the Whitneys. The Hitchcocks built a steeplechase training track on their Aiken property and trained young thoroughbred horses imported from [[England. Fond of fox hunting, they also established the Aiken Hounds and in 1916 received official recognition from the Masters of Foxhounds Association of North America.As an owner and trainer of racehorses, in 1895 Thomas Hitchcock began a career that would last for 47 years until his death in 1941. Although he did train horses for [[flat racing, he built his reputation in steeplechasing. He was the owner or trainer of a number of top horses including the Hall of Fame gelding Good and Plenty with whom he won the 1906 American Grand National.