Carter was born in Wise, Richmond County, Virginia in 1808 to Col. Landon Carter II and his second wife, the former Mary Burwell Armistead. After private education locally, he went to boarding school at Phillips Academy in Andover, Massachusetts, then began studies at the University of Virginia but was expelled after a rules violation. He then studied law under Henry St. George Tucker from 1827 until 1829. He married orphan Richardetta Louisa De Butts in Loudoun County on February 12, 1834. Initially, he farmed near the border between Fauquier and Loudoun counties, but eventually moved to her late father's Virginia estate, which he probably named "Crednal" after his grandmother's Herferdshire County, England village, after the death of his wife's mother in 1845. His wife died young, as did their daughter Mary Winn Carter and an infant son Edgar Marshall Carter, although one son survived, Confederate Col. Richard Welby Carter. John A. Carter owned 28 enslaved people in 1840, 13 enslaved black people in 1850, and 25 enslaved people in 1860. In the 1860 federal census, Carter owned $37,000 in real property and 26,585 in personal property, including slaves, and his household also included his son R. W. Carter, Elizabeth Simpson as well as her daughter Virginia.
Career
After admission to the Virginia bar, Carter began his law practice in his native Richmond County, then relocated to Middleburg in Loudoun County, Virginia, and practiced in Leesburg, the county seat. Carter twice served two terms in the Virginia House of Delegates, first winning election in 1842 alongside William H. Gray and Daniel Miller and then won re-election in 1843, but this time along with John Grubb and A. Sidney Tebbs. Loudoun County voters elected Carter in 1850, to the Virginia Constitutional Convention of 1850, as one of their three delegates. Despite his Tidewater ancestry, he spoke in favor of universal white manhood suffrage and allowing the western Virginia counties a majority in the House of Delegates. Carter was then elected to the state Senate in 1859, serving part of a single term before the AmericanCivil War. A Unionist in the Virginia Secession Convention of 1861, Carter voted against secession during both the votes on April 4 and April 17. Shortly after Virginia voted for secession, his Virginia Military Institute educated son, Richard Welby Carter, who had already organized a cavalry company to defend his northern Piedmont region, volunteered to join the Confederate States Army. The younger Carter would serve until nearly the war's end, despite two terms as prisoner of war, rising in rank from Captain of Company H of the 1st Virginia Cavalry to Major, Lt. Col. and finally Colonel, and although at war's end he was imprisoned at the Old Capital prison in Washington D.C. and at Camp Delaware. He was ultimately pardoned and married, but his father survived him. The family's farm, Crednal, was near the heart of the Battle of Unison in 1862, as well as during the Battle of Upperville, and was probably burned during the fall of 1864 by troops under Maj. Gen. Wesley Merritt because of Carter's hospitality toward J.E.B. Stuart in 1862 and John Singleton Mosby. After the American Civil War Carter also won election as a Conservative in 1873, taking office the following New Year's Day alongside Mathew Harrison. He won re-election in 1875, this time alongside William Mathew, who was left out of the 1873 election. However, he was defeated the following year by John R. Carter of Philomont, who had been an ardent Confederate and whom voters had rejected before the war.
Death
Although Carter spent his final years at Crednal, he is listed in the 1880 census at his son Richard W. Carter's home, Mercer, in Loudoun County, with Richard's wife Sophie and their daughters and young sons, although his Crednal estate was improved in the 1870s. John Armistead Carter died at Crednal in 1895, survived by several grandchildren and Welby Carter's widow Sophie, who continued to manage Crednal until her death in 1928. Armistead Carter is buried at the private Carter family cemetery at Crednal, as would be his granddaughter Fannie Carter Marshall. Nearby Willisville, Virginia may have been founded by former slaves at Crednal, which also has a slave graveyard with only one marker.