US Congressman, Lawyer. He was born one of four children in Franklin County, Pennsylvania, to Archibald Thomson (1755-1801), a Revolutionary War veteran, and his wife Mary Ann Andrews Thomson (1767-1805), on January 12, 1788. He was educated locally but received only limited schooling. Both his parents passed away when he was in his early teens. He apprenticed as a sickle maker, bagging hook, reaping-hook, or grasshook, which is a single-handed agricultural tool designed with variously curved blades and typically used for harvesting, or reaping, grain crops, or cutting succulent forage chiefly for feeding livestock, either freshly cut or dried as hay when he was fifteen years old with his Uncle Alexander Thomson. He was a self-taught scholar of Latin and Greek languages. He was hired by Reverend Isaac Grier to be a tutor at his classical school in the Cumberland Valley, Pennsylvania. While there, he also furthered his education. After three years, he moved to Bedford, Pennsylvania, where he taught languages at the Bedford Classical Academy in Bedford, Pennsylvania. He also studied law under Judge James Riddle in Bedford, Pennsylvania, was admitted to the bar in 1816, and commenced his practice of law in Chambersburg, Pennsylvania. He then entered politics and served in several local political offices including as a Member of the State Legislature in 1820, and a Member of the Pennsylvania State House of Representatives from 1823 to 1824. He then decided to run for a seat in the United States Congress and was elected to succeed the outgoing United States Representative John Tod (1779-1820), due to his resignation in 1824. He was elected on October 12, 1824, to fill the seat left vacant by United States Representative John Tod and was elected the same day to his next term. A Member of the Democratic-Republican Party, he then served Pennsylvania's 18th District in the United States House of Representatives from December 6, 1824, to March 3, 1825. A Member of the Jacksonian Party, he was then reelected and served Pennsylvania's 19th District in the United States House of Representatives from March 4, 1825, to May 1, 1826. Following his terms in the United States Congress had expired he was succeeded in office by the incoming United States Representative Chauncey Forward (1793-1839), on December 4, 1836. A special election was held to fill the resulting vacancy on October 10, 1826, the same day as the general elections to the 20th Congress. After leaving the United States Congress, he was immediately commissioned a District Court Judge of the District Court of the City and County of Lancaster, Pennsylvania, York County, Pennsylvania, and Dauphin County, Pennsylvania, on May 2, 1826. He was also commissioned a President Judge of the District Court of the Sixteen Judicial District, which was composed of Franklin County, Pennsylvania, Bedford County, Pennsylvania, and Somerset County, Pennsylvania, and he served in the position from June 25, 1827, to 1841. He lived in a mansion in Chambersburg, Pennsylvania, that was used as his residence, offices for his private practices, and a law school. His instructions consisted of oral instructions and examinations. His school became the law department of Marshall College in Lancaster, Pennsylvania. He continued to be active in several different pursuits until his death. He passed away in Chambersburg, Pennsylvania, on August 2, 1848, at the age of 66, and he was buried in the Falling Spring Presbyterian Church Cemetery in Chambersburg, Pennsylvania. He was married to Abigail Blythe Thomson from October 21, 1817, until her death. The couple had no children. He was also married to Jane Graham Thomson (1804-1883), and together they had seven children including Anna Thomson (1843-1861), George Graham Thomson (1826-1881), and Frank Thomson (1841-1899), who was a railroad executive from the United States, and the sixth president of the Pennsylvania Railroad. He was the grandson of immigrant Alexander Thomson who arrived from Scotland in 1771 and settled with his wife and 12 children near Chambersburg, Pennsylvania.