Edelbert Harthorn was born in Maine on July 25, 1839; he was one of at least nine children of Abigail (Shumway) and Daniel Harthorn. Both Edelbert and his father served in the Maine Infantry during the Civil War. Following the war, many of the Harthorn siblings moved to Minnesota, but they soon headed west to Dakota Territory. One of the brothers began the first grist mill in Sioux Falls in 1873.

Edelbert Harthorn married Augusta Campbell and the couple had two children: Frank Lewis (born 1864 in Anoka, Minnesota) and Edelbert "Dell" Henry (born 1875 in Sioux Falls, Dakota Territory). The "two Mr. Harthorns" from the "Little House"® books were Edelbert Melville Harthorn (1839-1925) and his eldest son, Frank Lewis Harthorn (1864-1950). The two were among the first settlers to arrive in De Smet, Dakota Territory, in the spring of 1880 (see By the Shores of Silver Lake, Chapter 24, "The Spring Rush").

Leaving the rest of the family in Sioux Falls, father and son arrived at the townsite of De Smet with a load of lumber with which to build a dry goods store. Because there was no place else to stay, they boarded with the Ingalls family in the Surveyors' House. At the time, Edelbert Harthorn contracted with Western Town Lots Company to purchase Lot 11, Block 1 in De Smet. The official deed of sale in June 1880 was between Albert Keep (attorney) and Frank Harthorn, who was 17 years old at the time. Officially called "Harthorn & Son," the store was referred to as the "Red Front Store" because of its bright red paint. The store was one story, frame, with two rooms.

In the summer of 1883, Frank sold his interests in De Smet and went into business with his future father-in-law, George Burd of Lake Preston. October 1883, Frank Harthorn married Mabel Kate Burd (born 1865), daughter of Samantha and George Burd. An announcement in the Lake Preston (Dakota Territory) Times read:

Married. Harthorn – Burd. In Lake Preston, Dakota, on Saturday, October 28, by Rev. J. T. Otis, Mr. Frank S. Harthorn and Miss Mabel K. Burd, all of the above place. They took the east bound passenger and spend a few days in Lake Benton, Minn., returning yesterday. In the marriage of the above we need but recognize “In union there is strength.” Though being in Lake Preston but a short time, they have gained the esteem of all who have made their acquaintance. The bride is a daughter of Mr. and Mrs. G. W. Burd. The groom is of the firm Harthorn and Burd and a promising young man of able business qualities. Congratulations were free upon their return and the best wishes of all will go with them through life. The Times acknowledge the customary offering in response.

In These Happy Golden Years, Laura Ingalls Wilder refers to Mabel as "May Bird" (see Chapter 11, "Jingle Bells"). Although they spent the first year of their marriage in Lake Preston, the couple - along with Mabel's parents - moved to De Smet the following year. George Burd purchased Royal Wilder's former feed store building and property in 1909.

Frank and Mabel had five children: Jessie (born 1884), Mary (born 1887), Frances (born 1897), Gordon (born 1900), and Lewis (born 1906). The Harthorn family lived on Second Street in De Smet. Frank was an avid bicycle rider; he was also foreman of the De Smet Fire Department for many years.

Following the death of his wife, Edelbert Harthorn and his son Dell moved to California. In 1906, Edelbert married Phoebe Shumway in Seattle, Washington. Phoebe and Edelbert Harthorn both died in Portland, Oregon, in August 1925.

In 1913, Frank Harthorn bought a "ten cent and variety store" in Livingston, Montana, and the Harthorns left De Smet. A notice in the De Smet News (September 26, 1913) reads:

F.L. Harthorn is here for a few days looking after collections. He had been in Minneapolis a week purchasing holiday goods for his store in Livingston, Montana. Mr. Harthorn says he is highly pleased with his new location, and that his business is far better than he had looked for.

In 1916, they left Montana , however, and relocated to Seattle, where the whole family operated a movie theater for many years. In 1917, daughter Jessie wrote to Carter Sherwood, editor of the De Smet News that "...Gordon runs the machine, Frances sells tickets, Mrs. takes tickets, Lewis ushers and Dad bosses the bunch."

Mabel Harthorn died in 1947, Frank in 1950. They are buried in Forest Lawn cemetery in Seattle.