James Thomas McCulloch was born 28 Dec 1858 on a farm near Sheers Cross Roads in Westmoreland County, Pennsylvania to Joseph and Harriet (Hudson) McCulloch. James was educated at the Delmont Academy, Delmont, Pennsylvania, and at Westminster College, New Wilmington, Pennsylvania, where he attended school up to the age of twenty-one. He then taught school for one year at the Leechburg Academy after which he entered the law office of Crosby and Crosby at Leechburg, Pennsylvania, where he remained for two years.

In 1884 he moved to Minnesota and was in charge of the schools at New York Mills, Otter Tail county, for three years. He then was principal of the high school at Perham, Otter Tail, Minnesota. He ran as the democratic candidate for county superintendent of schools in 1888 but was defeated. He was interested in politics and in 1880 made 43 speeches in the Garfield-Hancock campaign.

On 28 Aug 1887 at Wahpeton, Dakota Territory, he married Harriet "Hattie" Mae Carnahan of Leechburg, Pennsylvania. She was born 3 Jul 1866 near Leechburg, Pennsylvania, to Adam and Esther (Long) Carnahan. At age 17 she received her teaching credential and taught in the rural schools of Westmoreland County, Pennsylvania. In 1886 she went by train to Underwood, Minnesota, to visit the John Wilson family, former neighbors in Pennsylvania, and stayed to become school principal at Battle Lake. She planned to teach in Fergus Falls but with her marriage instead taught in the Perham schools where her husband was principal. She taught until 1890 when James McCulloch was admitted to the Minnesota bar and they moved to Pelican Rapids where he practiced law for eight years.

James became interested in western North Dakota while looking after the interests of his brother-in-law, Capt. Chauncey Baxter, who was serving in the Spanish-American War. In 1898 he established a law office at Washburn, North Dakota, the first lawyer to do so. His family moved to Bismarck in 1901 and when the railroad was built into Washburn and the family home was built there. In 1900 he was appointed states attorney of McLean county for four years. He was instrumental in interesting W.D. Washburn of Minneapolis in building the Bismarck-Washburn Great Falls railroad from Bismarck to Washburn. This line later became part of the Soo Railway. In 1902 he organized the First National Bank of Washburn and was a director until ill health forced his resignation. In 1903 he was one of the organizers of the Security Abstract and Loan Company of Washburn and served as president. In 1906 he was one of the agents for the sale of 35,000 acres of land on the old Fort Stevenson Reservation. He had various law partners at times but in 1915, his son Hugh joined him in his law practice which became McCulloch and McCulloch.

When World War I broke out he was asked to organize the Red Cross in McLean County; he also was appointed by the government as a member of the "Four Minute Men", a group of patriotic speakers. He was an organizer of the Liberty Loan drives and did much work to help administer the draft law in McLean County. He was also a member of many fraternal organizations.

In 1924 he began to retire from so many business affairs but still remained active in his law practice until his stroke 25 Feb 1939 and then the death of his son Hugh in October 1939 was a blow he did not recover from. He died 8 March 1940. At his funeral the hymn "The Ninety and Nine" by I.D. Sankey was sung. As a young man James McCulloch was one of a group who sang frequently at evangelist meetings conducted by Moody and Sankey in western Pennsylvania, and this was his favorite hymn. James McCulloch and his wife were lifelong Presbyterians, the religion of their Scots-Irish forefathers.