The current seat was created in boundary changes in 1983, as part of an expansion of Northern Ireland's constituencies from 12 to 17, and was predominantly made up from parts of North Antrim and South Antrim. Since further revisions in 1995 (when it lost part of the district of Newtownabbey to the North Belfast constituency) it now covers the entirety of the districts of Larne and Carrickfergus, as well as part of Newtownabbey and Moyle.
Prior to the 2010 general election the Boundary Commission originally proposed two significant changes for East Antrim. In the south of the constituency it was proposed to transfer a further part of Newtownabbey to the North Belfast constituency whilst in the north the seat would have gained the Glens and Ballycastle in Moyle district from North Antrim. East Antrim would have been renamed 'Antrim Coast & Glens'. However this latter part of the proposal raised many questions, with some already arguing that the Glens have no natural ties to Jordanstown (and in 1995 the previous Boundary Commission cited this very reason when rejecting such a proposal).
Following consultation and revising the recommondations, the new boundaries for East Antrim were confirmed and passed through Parliament by the Northern Ireland Parliamentary Constituencies Order as follows:
The whole district of Carrickfergus
The whole district of Larne
Glenaan, Glenariff, and Glendun from the Moyle district
From Newtownabbey, the wards of Jordanstown, Monkstown, and Rostulla
Sinn Féin contested the general election of 1918 on the platform that instead of taking up any seats they won in the United Kingdom Parliament, they would establish a revolutionary assembly in Dublin. In republican theory every MP elected in Ireland was a potential Deputy to this assembly. In practice only the Sinn Féin members accepted the offer.
The revolutionary First Dáil assembled on 21 January 1919 and last met on 10 May 1921. The First Dáil, according to a resolution passed on 10 May 1921, was formally dissolved on the assembling of the Second Dáil. This took place on 16 August 1921.
The constituency is overwhelmingly unionist, with the combined votes for nationalist parties rarely exceeding 10%. However there have been above average votes for parties outside the traditional unionist block, such as the Alliance and the Conservatives. In the local government elections for the equivalent area many votes often go to independent candidates or groups such as the Newtownabbey Ratepayers Association. While the SDLP sprung a surprise in 1998 by overtaking a DUP candidate to win the final seat due to Ulster Unionist transfers – the first time that any nationalist candidate has benefited in this way.
The main interest in Westminster Elections has been the contest between the Ulster Unionist Party and the Democratic Unionist Party. In 1983 the UUP were only 367 votes ahead of the DUP. As part of a pact to oppose the Anglo-Irish Agreement the DUP did not contest the seat until 1992 but they still failed to come close, though in the 1996 elections to the Northern Ireland Forum they were only slightly behind the UUP. But in the 2001 general election they achieved an astonishing result when they came with 128 votes of winning the Westminster seat, despite not having targeted it. In the 2003 Assembly election they followed this up by gaining two additional MLAs and outpolling the UUP for the first time.