Porter, Alexander (1785–1844), US senator, was born 24 June 1785, one of seven children of James Porter (qv), presbyterian minister, and his wife Anna Knox of Dromore (d. 1823). Though not a United Irishman, James Porter was implicated in the 1798 rebellion, court-martialled, and executed on 2 July. Local tradition records Alexander, just short of his thirteenth birthday, carrying colours at the battle of Ballynahinch (13 June 1798), then fleeing to Ballandrait, where he was recognised by a soldier who did not, however, denounce him. He and his younger brother James were then concealed by their father's cousin, Andrew Stilley, in the house of Donald McGinley, a tailor in Guystown, until they succeeded in escaping in 1801 with their uncle Alexander Porter to Nashville, Tennessee. There, the elder Porter established himself as a merchant, and Alexander worked in his store, studied law, and was admitted to the bar in 1807. He practised three years in Nashville before moving to the New Orleans territory about 1810. He gained the confidence of the French Creole population, who sent him as their delegate to the Louisiana constitutional convention of 1811–12, where he successfully pleaded the Creole case. In 1816 he finally gained American citizenship and that year began a brief stint (1816–18) in the lower branch of the state legislature before serving as justice in the Louisiana supreme court (1821–33). He made an important contribution to Louisiana jurisprudence, especially through his research into Spanish law.
An active Whig, Porter was in frequent dispute with the Louisiana Jacksonians; he opposed Edward Livingston's 1825 Louisiana civil code and code of practice as anti-democratic and preserving too much Latin influence on the state. He had come to reject his early support of Creole dominance, believing it a reversion to the colonial past. The Jacksonians' failure to unite behind a single candidate after the death of Senator Joseph Johnston (May 1833) allowed Porter to get into the senate with a two-vote majority. He served three years (6 January 1834–5 January 1837) and devoted himself to supporting the federal union. He also pushed for tariff protection of American industry, privatisation of public lands, and the recognition of the independence of Texas. On the slavery issue, he maintained the position of his southern colleagues, denouncing abolitionists as hypocrites and fanatics. He was himself master of 160 slaves on one of the handsomest sugar plantations in Louisiana, the 2,000-acre ‘Oak Lawn’, where he indulged his passion for thoroughbred horses. In private correspondence he espoused emancipation but counselled the utmost caution in bringing it about.
The whig press portrayed Democratic attacks on Porter as slurs against Ireland, and Porter's high standing among the Irish of Louisiana helped win immigrant Irish votes for Edward Douglass White in the 1834 state elections, although subsequently the Irish reverted to voting Democrat. Porter, while proud of his Irish heritage, was, like other Whigs, wary of the disruptive potential of immigrants, and favoured a long waiting period for their naturalisation.
He resigned from the senate in January 1837 due to atherosclerosis and spent the next few years travelling to Cuba and England to improve his health. A Democratic Louisiana legislature elected him to the 1843 senate – a tribute to his popularity – but his health did not permit his taking the seat and he died at Oak Lawn on 13 January 1844. He was predeceased by his wife, Evalina Baker (m. 1815) of St Martinville, Louisiana, and by his two daughters, leaving his brother, James Porter (d. 1849), a distinguished Louisiana attorney general, to inherit the estate.
Porter was a noted linguist, traveller, and bibliophile. His correspondence, which is held in the Josiah Stoddard Johnston papers at the Historical Society of Pennsylvania and in collections in the Library of Congress, displays great wit and charm.