Alexander Carnahan (1789-1879) was the third son born to David and Agnes (McGahey) (born 1757) Carnahan. David, who was born in 1747 in County Antrim, Ireland, emigrated to America around 1770 and served as a private in the Revolutionary War, including the battle of Brandywine. In Ireland he was a cooper, but in the States a farmer. In 1789, David and Agnes moved to Allegheny County from Carlisle, Pa., and purchased 400 acres from Isaac Seller-one of the first settlers in the area. Called “The Experiment,” the farm was located three and a half miles from Pittsburgh in what is now Banksville/Green Tree. When David died, his three sons-William (a ruling elder at MLEPC and husband of Mary Brown who died 1854), Joseph and Alexander-inherited 250 acres (the rest had been previously sold). The family’s log cabin probably stood where Winchester Drive in Banksville is now located. There is no tombstone for David and Agnes, but David is listed as a MLEPC original trustee, so there is a good chance he and Agnes are buried here as well. David and Agnes had 11 children including daughter Sarah who married Charles Frew. Two of Sarah and Charles’ six children are buried here–John, who died at age 31, and William, who died in 1820 at the age of 13.
Alexander farmed his land, served in the War of 1812 under Captain Jeremiah Ferre, (he was later promoted to colonel), was a justice of the peace, a county commissioner for Lower St. Clair Township and served in the Pennsylvania Legislature. Alexander was a member of the MLEP Church for 70 years and chairman of the Session. In 1812, he married Nancy Smith (1793-1849) of Westmoreland County and they had seven children, at least three of whom are buried in St. Clair Cemetery-Sarah A. (who died at age 21); Agnes (see below); and William (1822-1896 or 1865), who married Margaret McClure Bigham (July 11, 1827-March 16, 1887) on Sept. 26, 1849. William and Margaret (who was born near Gettysburg) had eight or nine children (two of whom settled in Dewey County, Oklahoma) including James Bigham Carnahan (June 28, 1850-May 11, 1924); Agnes Eliza Carnahan (1854-1915); Anna Margaret Carnahan (Feb. 17, 1856-Dec. 8, 1910); David Paxton Carnahan (Nov. 19, 1860-Feb. 25, 1929) who married Emma S. Stamm (1865-1942) on Oct. 31, 1919; and William Boyd Carnahan who married Anna Margaret McCormick” on May 11, 1893. Anna is the daughter of Joseph and Mary McCormick. Anna and William moved to Kansas where Anna died at age 38. William remarried five years later.
After Nancy died in 1849, Alexander, at age 56, married Eliza Banks. Alexander laid out the Banksville area after the Civil War and local lore says he named the area “Banksville” in honor of his second wife’s family; Carnahan Road memorializes Alexander’s family.
In 1842, Alexander and Nancy’s daughter Agnes (1815-1873) married James Watt (1814-1890). Agnes and James had several children, including Alex C. (who died at age 9), George C. (1853-1889) and “twin brothers” who died March 4 and 6, 1844. Buried near the Alexander Carnahan obelisk is another Watt child, who died at age 3. While the name and death date are illegible, the inscription reads: “Suffer the little children to come unto me and forbid them not for such is the Kingdom of Heaven.”