Baldwin was born on January 12, 1871, in the Baldwin house at the Paliuli sugar mill, between the towns of
Pāia and
Makawao, on
Maui,
Kingdom of Hawaii. His father
Henry Perrine Baldwin and uncle Samuel Thomas Alexander had established
Alexander & Baldwin (A&B) one of the "
Big Five" corporations that dominated Hawaii economics in the early twentieth century, in 1869. His father was son of early missionary
Dwight Baldwin, and his mother Emily Whitney Alexander was daughter of early missionary
William P. Alexander. Baldwin was educated in
Honolulu at
Punahou School. His parents sent him to
Phillips Academy in
Andover, Massachusetts, from which he graduated in 1889. In 1894, Baldwin obtained a degree at the
Massachusetts Institute of Technology, where he was a member of
Chi Phi fraternity. He returned to work for his father and uncle as manager of the Hamakuapoko sugarcane
plantation from 1897 to 1904. After A&B took control of the larger Hawaiian Commercial and Sugar Company, the Hamakuapoko mill was merged with the larger Pāia mill in 1905, and he became president of the combined operation called the Maui Agricultural Company. In 1916, during
World War I, he served as colonel of the 3rd Regiment of the
Hawaii National Guard. On July 19, 1897, he married Ethel Frances Smith (1879–1967), daughter of lawyer
William Owen Smith in
Honolulu — his younger brother Samuel would later marry sister Katherine Smith. They had one daughter, Frances Hobron (1904–1996) who married J. Walter Cameron (1895–1976), manager of the pineapple plantation in
Honolua. Cameron's company
Maui Pineapple Company merged with Baldwin's pineapple business to become the
Maui Land & Pineapple Company. The Camerons' son Colin Cameron founded the
Kapalua Bay Hotel & Villas resort. The pineapple business continued until 2009. == Politics ==