The children's names and dates of birth and death are recorded in a family Bible kept by their son Harmon, who in turn gave it to his son John F. Younkin who passed it on to a cousin, Colwell Seveno Younkin. [View the original handwritten list.]

The Younkins lived on a farm of 134 acres, inherited from John's father in 1811 but purchased through a legal patent in April 1836. The acreage adjoined farms of Michael Ansell, Jacob Younkin, Nicholas Hartzell and others. The tract was rich in timber, with stands of sugar maple, chestnut, hickory and other trees. He also held a legal interest in land inherited from his father and late brother Henry Younkin, with a two-story house, cabin barn and other buildings standing on about 100 acres of cleared land. 

At the age of 52 years, 10 months and six days, John J. died on Dec. 12, 1839. His remains were buried in the Lemmon Farm cemetery along Humbert Road near Kingwood. The graveyard in the 1930s was known as the "Brougher Cemetery" but today is named "John Younkin Cemetery." Because three of John's children were underage at the time -- Herman, Elizabeth and Jonas -- Henry L. Holbrook was assigned as their guardian. 

Boast not another day,  Nor call tomorrow thine,  Thou mayest be snatched away  By sudden death like mine.

John's epitaph, 1838

Text was inscribed on his grave marker, a poem which was popular on tombstones of that era, that also had been used on his brother Henry's marker a few years earlier:

After John J.'s demise, his son Jacob J. Younkin and Michael Sanner served as administrators of his estate. The 134-acre farm was purchased at auction by high bidders Joseph and Samuel Reymond. His other tract was offered for sale via advertisements in the Somerset Herald and Farmers' and Mechanics Register. The ad noted that the 299-acre farm, "on which are erected a two-story house, cabin barn and other buildings, [contains] about one hundred acres of clear land." It also advised that one third of the purchase price would become a principal investment, with "the interest thereof to be paid to the widow annually during her life time, and at her death the principal to be equally divided among the heirs and legal representatives of the deceased..." It was bought in 1846 by Joseph Pringey, husband of the deceased's first cousin Margaret Rebecca "Peggy" (Younkin) Pringey. 

Among those who attended his farm sale in 1846, or made other financial claims against his estate, were kinsmen Henry Younkin, Garrison Smith, Jacob Younkin of Jacob, Henry Minerd, Elijah Younkin, Jacob J. Younkin, John F. Kreger, E.S. Younkin, Herman Husband, Charles Minerd, Andrew Schrock and John Minerd.

Polly outlived her husband by more than three decades. In about 1866, her granddaughter Joanna Younkin married Yankee John's grandson Ephraim Miner. In 1870, federal census records show an elderly Polly in the household of her daughter Nancy Johnson in Upper Turkeyfoot. 

Polly passed on Nov. 14, 1870, at the age of 85, and was laid to rest in the family burying ground.

John and Polly were remembered in 1899 when named and described in a chapter about their grandson, John F. Younkin, in the book Biographical Review: Containing Sketches of Leading Citizens of Bedford and Somerset Counties, Pennsylvania, produced in Boston by the Biographical Review Publishing Company. The entry read: 

The grandfather was John J. Younkin, a native of Virginia, who came with his parents to Somerset County when a young man and engaged in farming. He married Polly Hartzell, a representative of a German family. Her father, John Hartzell, served in the American army all through the Revolutionary War.

In August 1970, the Laurel Messenger newsletter of the Historical and Genealogical Society of Somerset County published excerpts from old Somerset Herald articles, including a notice of John's estate settlement, dated Oct. 21, 1845.