Longford–Westmeath is a parliamentary constituency represented in Dáil Éireann, the lower house of the Irish parliament or Oireachtas. The constituency elects 4 deputies (Teachtaí Dála, commonly known as TDs) on the system of proportional representation by means of the single transferable vote (PR-STV).

The constituency previously existed from 1921 to 1937 and from 1948 to 1992, but was abolished for the 1992 general election. It was re-created by the Electoral (Amendment) Act 2005 which gave effect to the 2004 Constituency Commission Report on Dáil Constituencies, and was first used in its current form at the 2007 general election.^[1][2][3] It contains the County Longford portion of the former Longford–Roscommon constituency, and most of the former Westmeath constituency apart from the north-eastern area around Castlepollard and Delvin, which became part of the new Meath West constituency.

The Electoral (Amendment) (Dáil Constituencies) Act 2017 defines the constituency as:^[4]

"The county of Longford;

and, in the county of Westmeath, the electoral divisions of:

Athlone East Rural, Auburn, Ballybroder, Bellanalack, Carn, Castledaly, Glassan, Kilcumreragh, Killinure, Moate, Mount Temple, Moydrum, Muckanagh, Tubbrit, Umma, in the former Rural District of Athlone No. 1;

Ardnagragh, Ballymore, Doonis, Drumraney, Noughaval, Piercetown, Templepatrick, Winetown, in the former Rural District of Ballymore;

Boherquill, Coole, Coolure, Finnea, Glore, Knockarrow, Rathowen, Street, in the former Rural District of Coole;

Ardnaglew, Ballinalack, Ballykilmore, Ballymorin, Ballynagore, Belvidere, Carrick, Castle, Castlelost, Castletown, Churchtown, Cloghan, Clonfad, Clonlost, Derrymore, Dysart, Emper, Enniscoffey, Gaybrook, Glenlough, Greenpark, Griffinstown, Heathstown, Hopestown, Huntingdon, Jamestown, Kilbeggan, Kilbixy, Killare, Killucan, Kinnegad, Knockdrin, Lackan, Lauree, Middleton, Milltown, Mullingar Rural, Mullingar North Urban, Mullingar South Urban, Multyfarnham, Newtown, Owel, Portloman, Raharney, Rahugh, Rathconrath, Russellstown, Skeagh, Sonna, Stonehall, Streamstown, Taghmon, Tullaghan, Woodland, in the former Rural District of Mullingar;

and Athlone East Urban, Athlone West Urban."

In the Constituency Review Report 2023, the Electoral Commission recommended that the electoral divisions of Westmeath in the Meath West constituency should be transferred to the Longford-Westmeath constituency, thereby making the constituency comprise the entire counties of Longford and Westmeath for the first time since 1980. It was also allocated an additional seat to become a five seat constituency.^[5]

For the next general election, the Electoral (Amendment) Act 2023 defines the constituency as:^[6]

"The county of Longford and the county of Westmeath."

• Dáil constituencies
• Elections in the Republic of Ireland
• Politics of the Republic of Ireland
• List of Dáil by-elections
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