James Wilson McArthur was born in Philadelphia, the son of John McArthur and Elizabeth Wilson.
McArthur enrolled in 1861 as a member of the College Class of 1865, but left during his sophomore year. He was a member of the Zelosophic Society.
The 1870 census for Philadelphia’s eighth ward lists James W. McArthur living in the household of John McArthur and his wife Elizabeth. John McArthur, born in Scotland, was a retired merchant, with real estate and personal estate valued at $60,000 and $10,000 respectively. Two young Irish women were live-in servants. James W. McArthur is described here as a twenty-six-year-old attorney. Twenty-nine-year-old John McArthur listed in the same household as a physician is probably John Alexander McArthur, A.B. 1861, son of John McArthur, who received his medical degree from Jefferson Medical College in 1864.