US Congressman. He was born one of six children in Shippensburg, Pennsylvania, to Joseph Duncan (1772-1818), and his wife Ruth Rippey Duncan (1773-1819), on July 22, 1806. He was educated locally, completing preparatory studies, and later attended the prestigious Jefferson College in Canonsburg, Pennsylvania, in 1825. Following his education, he moved to Newark, Ohio, in 1828, where he engaged in mercantile pursuits. He then decided to enter politics and was elected as a Member of the Ohio State House of Representatives serving the District of Licking County, Ohio, in that position in 1843. A Member of the Whig Party, he was an unsuccessful Candidate for election to the Ohio State Senate in 1844. He then decided to run for a seat in the United States Congress and was elected to succeed the outgoing United States Representative Columbus Delano (1809-1896), on March 4, 1847. A Member of the Whig Party, he then served Ohio's 10th District (Thirtieth Congress), in the United States House of Representatives from March 4, 1847, to March 3, 1849. He was an unsuccessful Candidate for reelection to the Thirty-First Congress in 1848. After his term in the United States Congress expired he was succeeded in office by the incoming United States Representative Charles Sweetser (1808-1864), on March 4, 1849. After his time in the United States Congress, he retired from politics and then returned to other pursuits until his death from consumption in Washington, D.C., a couple of months later on May 18, 1849, at the age of 45. Following his death, he was buried in a temporary burial vault at Congressional Cemetery in Washington, D.C., before being moved to his current burial location at the 6th Street Cemetery, also known as the Old Graveyard and Newark Graveyard in Newark, Ohio. He also has a cenotaph at the Woodlawn Cemetery in Zanesville, Ohio. On his passing one of his newspaper obituaries of the time said of him, "He won his way to the confidence and respect of his fellow citizens; and passes from the busy scenes of life respected and beloved by a large circle of friends and acquaintances." He was married to Mary Munro Convers Duncan (1812-1856), on October 18, 1832, in Muskingum County, Ohio, and the couple would have six children together, Ellen Augusta Duncan (1839-1908), Mary Converse Duncan (1841-1867), Charles Converse Duncan (1843-1879), Alice Goddard Duncan (1846-1883), and Henry Convers Duncan (1851-1909).