Frelinghuysen was born in New York City to Peter H. B. Frelinghuysen and the former Adaline Havemeyer. Frelinghuysen's father was a banker who descended from 18th century Dutch settlers in Somerset County.[2][a] His siblings included his twin brother Henry O.H. Frelinghuysen, a philanthropist and civic leader,[4] George G. Frelinghuysen, and Frederica Frelinghuysen Emert.[5]
After practicing law in New York City, he served in the Office of Naval Intelligence from September 1942 to December 1945 obtaining the rank of lieutenant. He then studied at Columbia University, 1946–1947. He served as staff of the Foreign Affairs Task Force of the Hoover Commission in 1948 before returning to the private sector. He served as director of Howard Savings Bank in Livingston, New Jersey.[1][b]
In December 1959, when the Port of New York Authority's plans to develop a tract of woodlands and marsh near his estate in Morris County as an international airport serving the New York City region were exposed, Frelinghuysen participated in the opposition by the Jersey Jetport Site Association that was composed of local residents and conservationists,[18][19][20] which raised funds to purchase almost 3,000 acres of the targeted site and donated it to the federal government, to be preserved forever as park lands. With the defeat of the airport development initiative, that parcel became the initial portion of the Great Swamp National Wildlife Refuge, established by federal statute on November 3, 1960, in the middle of the development controversy.[16]
In January 1965, he was House Minority Leader Gerald Ford's choice for Minority Whip, but lost on a secret ballot of the Republican caucus by a vote of 70 to 59 to the incumbent Les Arends, who had held the post since 1943.[16][21]
He married the former Beatrice Sterling Procter, in Stockbridge, Massachusetts, on September 7, 1940.[6] She was a descendant of the founder of Procter & Gamble.[2] Their children include Peter Frelinghuysen II, a lawyer, and Rodney P. Frelinghuysen, a former congressman.[24] They lived in a 20-room Georgian Colonial home on 32 acres in Harding Township, New Jersey, designed by James W. O'Connor in 1948.[25]
^Frelinghuysen Sr., a Princeton graduate, was a classmate at Columbia Law School of President Franklin D. Roosevelt, who served as an usher at his 1902 wedding to Adaline Havemeyer. Frelinghuysen Sr. devoted himself to cattle breeding in addition to banking.[3]
^Howard Savings was founded as Howard Savings Institution in Newark in 1857.[7] It was purchased by First Fidelity Bancorporation of Newark in 1992.[8]