Almon Bradley Fargo was born on November 3, 1834, in Barre, New York, to Hiram Fargo and Electa Clark. His father was a farmer who owned $8,350 of real estate and $3,700 of personal property by 1860. Fargo grew up and attended school in Barre, and by 1850, he was working as a farmer. He married Elvira Northway around 1862, and they had at least four children: Ida, born around 1866; Edna, born around 1868; Bertrand, born around 1878; and Alma, born around 1880.
He enlisted in the Union army on August 30, 1862, and he mustered in as a private in Company D of the 151st New York Infantry on October 22. According to his service records, he was 5 feet, 4 inches tall, with auburn hair and gray eyes. The regiment took part in the Gettysburg campaign, the Battle of the Wilderness, the Battle of Spotsylvania Court House, the Battle of Cold Harbor, the siege of Petersburg, and the Appomattox campaign. He mustered out in Washington, D.C., on June 26, 1865.
Fargo settled in Clarendon, New York, after the war and resumed his work as a farmer. By 1870, he owned $3,900 of real estate and $915 of personal property. He died on November 26, 1901.