Isaac P. Simpson, lawyer and state representative, was born in Winchester, Kentucky, on April 24, 1832, to James and Mary L. (Caldwell) Simpson. The elder Simpson was a prominent lawyer in Kentucky and served in the state legislature as well as the state supreme court. Isaac Simpson was raised and educated in Winchester. In 1851 he graduated first in his class and delivered the valedictory address, at Center College in Danville, Kentucky. Afterward he studied law under his father and at Transylvania Law School in Lexington, Kentucky. In 1853 Simpson married Fannie Weir in Lexington. This couple had two sons and four daughters. In 1855 Simpson immigrated with his family to San Antonio, Texas, where he established himself as one of the leading citizens of the community. In addition to being a successful lawyer, Simpson was an active Presbyterian, Mason, and Democrat. In 1861 he won election as representative for Bexar County to the House of the Ninth Texas Legislature. He was reelected in 1863 and served in the Tenth Texas Legislature during which time he was a member of the Finance, Education, Judiciary, and Impressment of Slaves committees. He served until August 6, 1866. During the late 1870s Simpson was a partner with John Herndon James in the San Antonio law firm of Simpson and James, which handled the legal matters of the larger landholders in South and West Texas. Simpson died on March 12, 1896, in San Antonio and was buried at Alamo Masonic Cemetery there.