Sylvester Strong was born on October 7, 1843, in Michigan to George Strong and Emily Maxfield. His father was a speculator who owned $600 of real estate in 1860. The family moved to Milwaukee, Wisconsin, around 1850.
Strong enlisted in the Union army on August 5, 1862, and he mustered in as a private in Company G of the 20th Wisconsin Infantry later that day. The regiment took part in the siege of Vicksburg. He returned to Milwaukee after the war and married Harriet Sweney, and their son George was born around 1869.
By 1870, Strong was working as a bookkeeper, and he owned $1,000 of real estate and $200 of personal property. Harriet may have died sometime in the 1870s, and he married Sarah Allen. Their daughter Jane was born around 1880. They moved to Minneapolis, Minnesota, around 1883, and he became a prominent grain merchant there. They settled in Pacific Grove, California, by the early 1900s, and Strong worked as a real estate agent. Sarah divorced him in December 1906 “on the grounds of cruelty and desertion.” He married Bertha Norton in Los Angeles, California, on May 14, 1914. He died in California on August 4, 1923.