William Henry Harrison Larimer was born in Pittsburgh, Pennsylvania, on December 9, 1840, the son of General William Larimer (1809-1875) and Rachel McMasters. William H. H. Larimer left school at the age of 12 and moved to Kansas with his father in 1855. In 1858, they moved to Colorado, where they built the first house in what is now Denver. William H. H. Larimer left Colorado in 1859 and worked in the freight industry, moving cargo around the western territories. After 1867, he lived in Kansas and Texas, where he worked in the lumber and cattle industries and from 1871-1876, he operated a hotel in Independence, Kansas. In 1887, he moved to Kansas City, Missouri, where he became a partner in a livestock firm. He and his wife Mattie married on February 22, 1871, and had two children, Henry and Ann. Ann Larimer married George H. Gallagher, a business manager for a theatrical company, around 1900. William H. H. Larimer died on May 25, 1910.
William H. H. Larimer's sister, Rachel Larimer, married James Ross Mellon of Pittsburgh, Pennsylvania, the brother of Andrew W. Mellon. In the 1860s, James R. Mellon worked with his brothers in the real estate and coal business. He was a banker and railroad executive, but was mainly interested in his family's coal and timber investments.