James Bartholomew Mullen, Jr. was born in Michigan in February, 1852, exactly where is currently unknown. He was the first child of James Mullen, Sr. and Ann Pagnan Mullen. His father immigrated from Ireland to New York in 1849 during the Irish potato famine to avoid starvation. He made his way to Michigan where he met his wife, Ann Pagnan. Ann was of Indian origin, born in Canada. Little else is known about her. After their second child, Matilda, was born in 1854 the family moved to Portage, Columbia County, Wisconsin. In 1866, the family moved again to a farm in Watopa, Wabasha County, Minnesota.

In 1877, James B married Sarah Reynolds Langley who was born in Boston, Massachusetts on August 5, 1858. They moved to Monroe, Lyons, Minnesota about 170 miles west of Saint Paul where they began to farm. Their first child was Lucinda (Lucy) A born February 10, 1878. Their second child was Alex (Allen?) who was born on September 3, 1879. He died two months later on December 13, 1879. By 1885, James and Sarah were living in Faribault, MN near Saint Paul. By this time James was occupied as a butcher. Three more children had been added to the family by then, viz.: Rosey (1881- ), Fannie (1882- ), and Carie (1885- ). In 1895, the family was living at 662 Pine Street, Saint Paul, Ramsey, Minnesota. At this time four more children had been born, viz.: Albert (1887- ), Florence (1889- ) and Sarah (Sadie) (1892- ) and Agnes (1895- ). The last of ten children, Robert J Mullen (1897- ) was born in January, 1897. Afterward, the family moved several more times. In 1900, they lived in West Saint Paul, Dakota, Minnesota; in 1905 they lived in Mendota Village, Ramsey, Minnesota; then, finally they lived in Saint Paul, Ward 6, Ramsey, Minnesota. By 1905, James had changed his occupation from butcher to a dealer of patent medicines.

Based on family photos James B appeared to be a very proud father and senior member of the first American-born Mullen family. On May 19, 1928 Sarah died in Saint Paul. She was interred at the Calvary Cemetery. James went to live as a boarder at the residence of Charles H and Mary A Ball where he died on April 14, 1935. He too is interred at the Calvary Cemetery. Sadly, he and Sarah are buried in separate sites located on either end of the cemetery.