Charles Woodberry McLellan was born in Beverly, Massachusetts, on November 25, 1836. After graduating from Boston English High School he moved to Springfield, Illinois, in 1856, where he worked as a clerk for N. H. Ridgely and Company, a banking firm. During this time he met both Abraham Lincoln and his law partner William Herndon. According to a short memoir, McLellan "transacted business with Mr. Lincoln over the counter of the Ridgely Bank where I was a clerk, besides greeting him constantly and attending little social gatherings at his home."
In 1860, McLellan moved to Mobile, Alabama, where he eventually worked in the Quartermaster's Department of the Confederate Army until the end of the Civil War. During this time he corresponded with Abraham Lincoln's son Robert, who had left Springfield for Harvard University. In 1865 McLellan moved back north to New York City after obtaining a pass from his friend John Hay, now secretary to Abraham Lincoln. There he worked for A. M. Kidder and Company before founding the brokerage house Boody, McLellan and Company with David Boody.
Charles McLellan retired in 1906 to his home in Champlain, New York. By this time he had begun to amass one of the largest collections of Lincolniana in the United States, which included correspondence, official documents, broadsides, books, pamphlets, ballots, and engravings. He spent the final years of his life developing this collection, until his death in 1918.