Longyear was born in Lansing, Michigan on April 15, 1850, the son of U.S. Congressman John Wesley Longyear and Harriet Longyear. It's unclear how many siblings Longyear had but it is known that he had two brothers named Howard and James and a sister named Ida. Through his mother, Longyear was reportedly the great-great-great grandchild of the Scottish American soldierWilliam Munroe. He was one of the founders, c. 1890, of the Huron Mountain Club near Big Bay, Michigan. In 1906 he founded the ArcticCoal Company with long-time associate Frederick Ayer and several other small shareholders. John Munro Longyear was the main owner of the Arctic Coal Company with headquarters in Boston, Massachusetts. Longyear had visited Svalbard in 1901, and bought the Trondhjem Spitsbergen Kulkompani in 1906. Store Norske Spitsbergen Kulkompani started as a consortium of Norwegian investors in 1916. It purchased Arctic Coal Company's and Ayer and Longyear's lands and operations on Spitsbergen in that year. They went on to develop major coal-mining operations in the Advent Valley region and at Sveagruva, originally a Swedish coal-mining operation. His passport application, dated 1895, describes Longyear, then 45 years old, as 6" 0" tall with black and grey hair and brownish grey eyes.
Personal life
Longyear married Mary Beecher Longyear on January 4, 1879 in Battle Creek, Michigan. Mary was a Christian Scientist and a philanthropist, perhaps best known for her involvement in the publication of the first braille version of the KJV Bible. The couple had seven children together: Judith F. Longyear, Robert D. Longyear, Howard M. Longyear, Abby B. Roberts, Helen M. Paul, John B. Longyear, and John M. Longyear, Jr. Some sources list the Longyears as having only five children but this discrepancy is likely due to that Howard and John died young, Howard M. Longyear at 20 and John B. Longyear as a toddler. For some years, the family was accompanied by a nurse, a young German woman named Angela Nerling, who both lived and traveled with them. In the early 20th century, Longyear made the decision to move from Michigan, where his family lived in a stone mansion on the shores of Lake Superior, to Massachusetts. His wife Mary was reportedly unsettled by the idea of leaving the family's home and so, Longyear arranged for the home to be dismantled and transported 1,300 miles across the country by railroad to their new hometown and reassembled there in 1903. Longyear lived out the rest of his life in Brookline, Massachusetts.