Mid Antrim was a constituency of the Northern Ireland House of Commons. The House of Commons (Method of Voting and Redistribution of Seats) Act (Northern Ireland), 1929 introduced first-past-the-post elections for 48 single-member constituencies (including Antrim Mid). In terms of the then local government areas the constituency in 1929 comprised parts of the rural districts of Ballymena, Ballymoney and Larne. The division also included the whole of the urban district of Ballymena.