Full list of counties for the United Kingdom and Republic of Ireland. Run this SQL against your Magento database to replace the existing region text box in Magento with a drop down containing the values related to either the UK or Ireland.
Northern Irish counties will appear under United Kingdom and depending on website you may want to modify county names before importing.
-- Data for table `directory_country_region` INSERT INTO `directory_country_region` (`region_id`, `country_id`, `code`, `default_name`) VALUES (1000, 'GB', 'AB', 'Aberdeenshire'), (1001, 'GB', 'AN', 'Anglesey'), (1002, 'GB', 'AG', 'Angus'), (1003, 'GB', 'AR', 'Argyll'), (1004, 'GB', 'AY', 'Ayrshire'), (1005, 'GB', 'BN', 'Banffshire'), (1006, 'GB', 'BD', 'Bedfordshire'), (1007, 'GB', 'BI', 'Berwickshire'), (1008, 'GB', 'BR', 'Breconshire'), (1009, 'GB', 'BK', 'Buckinghamshire'), (1010, 'GB', 'BU', 'Bute'), (1011, 'GB', 'CN', 'Caernarvonshire'), (1012, 'GB', 'CT', 'Caithness'), (1013, 'GB', 'CM', 'Cambridgeshire'), (1014, 'GB', 'CG', 'Cardiganshire'), (1015, 'GB', 'CR', 'Carmarthenshire'), (1016, 'GB', 'CH', 'Cheshire'), (1017, 'GB', 'CL', 'Clackmannanshire'), (1018, 'GB', 'CN', 'Cornwall and Isles of Scilly'), (1019, 'GB', 'ANT', 'County Antrim'), (1020, 'GB', 'ARM', 'County Armagh'), (1021, 'GB', 'DOW', 'County Down'), (1022, 'GB', 'FER', 'County Fermanagh'), (1023, 'GB', 'DER', 'County Londonderry'), (1024, 'GB', 'TYR', 'County Tyrone'), (1025, 'GB', 'CU', 'Cumbria'), (1026, 'GB', 'DI', 'Denbighshire'), (1027, 'GB', 'DB', 'Derbyshire'), (1028, 'GB', 'DV', 'Devon'), (1029, 'GB', 'DO', 'Dorset'), (1030, 'GB', 'DA', 'Dumbartonshire'), (1031, 'GB', 'DU', 'Dumfriesshire'), (1032, 'GB', 'DR', 'Durham'), (1033, 'GB', 'EL', 'East Lothian'), (1034, 'GB', 'ES', 'East Sussex'), (1035, 'GB', 'EX', 'Essex'), (1036, 'GB', 'FI', 'Fife'), (1037, 'GB', 'FL', 'Flintshire'), (1038, 'GB', 'GM', 'Glamorgan'), (1039, 'GB', 'GL', 'Gloucestershire'), (1040, 'GB', 'GR', 'Greater London'), (1041, 'GB', 'GM', 'Greater Manchester'), (1042, 'GB', 'HM', 'Hampshire'), (1043, 'GB', 'HT', 'Hertfordshire'), (1044, 'GB', 'IV', 'Inverness'), (1045, 'GB', 'KN', 'Kent'), (1046, 'GB', 'KE', 'Kincardineshire'), (1047, 'GB', 'KP', 'Kinross-shire'), (1048, 'GB', 'KC', 'Kirkcudbrightshire'), (1049, 'GB', 'LA', 'Lanarkshire'), (1050, 'GB', 'LC', 'Lancashire'), (1051, 'GB', 'LE', 'Leicestershire'), (1052, 'GB', 'LN', 'Lincolnshire'), (1053, 'GB', 'LD', 'London'), (1054, 'GB', 'ME', 'Merionethshire'), (1055, 'GB', 'MR', 'Merseyside'), (1056, 'GB', 'MO', 'Midlothian'), (1057, 'GB', 'MO', 'Monmouthshire'), (1058, 'GB', 'MG', 'Montgomeryshire'), (1059, 'GB', 'MY', 'Moray'), (1060, 'GB', 'NN', 'Nairnshire'), (1061, 'GB', 'NR', 'Norfolk'), (1062, 'GB', 'NH', 'Northamptonshire'), (1063, 'GB', 'NU', 'Northumberland'), (1064, 'GB', 'NY', 'North Yorkshire'), (1065, 'GB', 'NO', 'Nottinghamshire'), (1066, 'GB', 'OR', 'Orkney'), (1067, 'GB', 'OX', 'Oxfordshire'), (1068, 'GB', 'PB', 'Peebleshire'), (1069, 'GB', 'PM', 'Pembrokeshire'), (1070, 'GB', 'PT', 'Perthshire'), (1071, 'GB', 'RD', 'Radnorshire'), (1072, 'GB', 'RN', 'Renfrewshire'), (1073, 'GB', 'RS', 'Ross & Cromarty'), (1074, 'GB', 'RX', 'Roxburghshire'), (1075, 'GB', 'SL', 'Selkirkshire'), (1076, 'GB', 'SE', 'Shetland'), (1077, 'GB', 'SH', 'Shropshire'), (1078, 'GB', 'SO', 'Somerset'), (1079, 'GB', 'SY', 'South Yorkshire'), (1080, 'GB', 'ST', 'Staffordshire'), (1081, 'GB', 'SN', 'Stirlingshire'), (1082, 'GB', 'SU', 'Suffolk'), (1083, 'GB', 'SU', 'Surrey'), (1084, 'GB', 'SR', 'Sutherland'), (1085, 'GB', 'TW', 'Tyne and Wear'), (1086, 'GB', 'WR', 'Warwickshire'), (1087, 'GB', 'WE', 'West Lothian'), (1088, 'GB', 'WM', 'West Midlands'), (1089, 'GB', 'WS', 'West Sussex'), (1090, 'GB', 'WY', 'West Yorkshire'), (1091, 'GB', 'WG', 'Wigtownshire'), (1092, 'GB', 'WL', 'Wiltshire'), (1093, 'GB', 'WO', 'Worcestershire'), (1094, 'IE', 'CAR', 'Carlow'), (1095, 'IE', 'CAV', 'Cavan'), (1096, 'IE', 'CLA', 'Clare'), (1097, 'IE', 'COR', 'Cork'), (1098, 'IE', 'DON', 'Donegal'), (1099, 'IE', 'DUB', 'Dublin'), (1100, 'IE', 'GAL', 'Galway'), (1101, 'IE', 'KER', 'Kerry'), (1102, 'IE', 'KID', 'Kildare'), (1103, 'IE', 'KIK', 'Kilkenny'), (1104, 'IE', 'LET', 'Leitrim'), (1105, 'IE', 'LEX', 'Leix'), (1106, 'IE', 'LIM', 'Limerick'), (1107, 'IE', 'LOG', 'Longford'), (1108, 'IE', 'LOU', 'Louth'), (1109, 'IE', 'MAY', 'Mayo'), (1110, 'IE', 'MEA', 'Meath'), (1111, 'IE', 'MOG', 'Monaghan'), (1112, 'IE', 'OFF', 'Offaly'), (1113, 'IE', 'ROS', 'Roscommon'), (1114, 'IE', 'SLI', 'Sligo'), (1115, 'IE', 'TIP', 'Tipperary'), (1116, 'IE', 'WAT', 'Waterford'), (1117, 'IE', 'WEM', 'Westmeath'), (1118, 'IE', 'WEX', 'Wexford'), (1119, 'IE', 'WIC', 'Wicklow'); -- Data for `directory_country_region_name` INSERT INTO `directory_country_region_name` (`locale`, `region_id`, `name`) VALUES ('en_US', 1000, 'Aberdeenshire'), ('en_US', 1001, 'Anglesey'), ('en_US', 1002, 'Angus'), ('en_US', 1003, 'Argyll'), ('en_US', 1004, 'Ayrshire'), ('en_US', 1005, 'Banffshire'), ('en_US', 1006, 'Bedfordshire'), ('en_US', 1007, 'Berwickshire'), ('en_US', 1008, 'Breconshire'), ('en_US', 1009, 'Buckinghamshire'), ('en_US', 1010, 'Bute'), ('en_US', 1011, 'Caernarvonshire'), ('en_US', 1012, 'Caithness'), ('en_US', 1013, 'Cambridgeshire'), ('en_US', 1014, 'Cardiganshire'), ('en_US', 1015, 'Carmarthenshire'), ('en_US', 1016, 'Cheshire'), ('en_US', 1017, 'Clackmannanshire'), ('en_US', 1018, 'Cornwall and Isles of Scilly'), ('en_US', 1019, 'County Antrim'), ('en_US', 1020, 'County Armagh'), ('en_US', 1021, 'County Down'), ('en_US', 1022, 'County Fermanagh'), ('en_US', 1023, 'County Londonderry'), ('en_US', 1024, 'County Tyrone'), ('en_US', 1025, 'Cumbria'), ('en_US', 1026, 'Denbighshire'), ('en_US', 1027, 'Derbyshire'), ('en_US', 1028, 'Devon'), ('en_US', 1029, 'Dorset'), ('en_US', 1030, 'Dumbartonshire'), ('en_US', 1031, 'Dumfriesshire'), ('en_US', 1032, 'Durham'), ('en_US', 1033, 'East Lothian'), ('en_US', 1034, 'East Sussex'), ('en_US', 1035, 'Essex'), ('en_US', 1036, 'Fife'), ('en_US', 1037, 'Flintshire'), ('en_US', 1038, 'Glamorgan'), ('en_US', 1039, 'Gloucestershire'), ('en_US', 1040, 'Greater London'), ('en_US', 1041, 'Greater Manchester'), ('en_US', 1042, 'Hampshire'), ('en_US', 1043, 'Hertfordshire'), ('en_US', 1044, 'Inverness'), ('en_US', 1045, 'Kent'), ('en_US', 1046, 'Kincardineshire'), ('en_US', 1047, 'Kinross-shire'), ('en_US', 1048, 'Kirkcudbrightshire'), ('en_US', 1049, 'Lanarkshire'), ('en_US', 1050, 'Lancashire'), ('en_US', 1051, 'Leicestershire'), ('en_US', 1052, 'Lincolnshire'), ('en_US', 1053, 'London'), ('en_US', 1054, 'Merionethshire'), ('en_US', 1055, 'Merseyside'), ('en_US', 1056, 'Midlothian'), ('en_US', 1057, 'Monmouthshire'), ('en_US', 1058, 'Montgomeryshire'), ('en_US', 1059, 'Moray'), ('en_US', 1060, 'Nairnshire'), ('en_US', 1061, 'Norfolk'), ('en_US', 1062, 'Northamptonshire'), ('en_US', 1063, 'Northumberland'), ('en_US', 1064, 'North Yorkshire'), ('en_US', 1065, 'Nottinghamshire'), ('en_US', 1066, 'Orkney'), ('en_US', 1067, 'Oxfordshire'), ('en_US', 1068, 'Peebleshire'), ('en_US', 1069, 'Pembrokeshire'), ('en_US', 1070, 'Perthshire'), ('en_US', 1071, 'Radnorshire'), ('en_US', 1072, 'Renfrewshire'), ('en_US', 1073, 'Ross & Cromarty'), ('en_US', 1074, 'Roxburghshire'), ('en_US', 1075, 'Selkirkshire'), ('en_US', 1076, 'Shetland'), ('en_US', 1077, 'Shropshire'), ('en_US', 1078, 'Somerset'), ('en_US', 1079, 'South Yorkshire'), ('en_US', 1080, 'Staffordshire'), ('en_US', 1081, 'Stirlingshire'), ('en_US', 1082, 'Suffolk'), ('en_US', 1083, 'Surrey'), ('en_US', 1084, 'Sutherland'), ('en_US', 1085, 'Tyne and Wear'), ('en_US', 1086, 'Warwickshire'), ('en_US', 1087, 'West Lothian'), ('en_US', 1088, 'West Midlands'), ('en_US', 1089, 'West Sussex'), ('en_US', 1090, 'West Yorkshire'), ('en_US', 1091, 'Wigtownshire'), ('en_US', 1092, 'Wiltshire'), ('en_US', 1093, 'Worcestershire'), ('en_US', 1094, 'Carlow'), ('en_US', 1095, 'Cavan'), ('en_US', 1096, 'Clare'), ('en_US', 1097, 'Cork'), ('en_US', 1098, 'Donegal'), ('en_US', 1099, 'Dublin'), ('en_US', 1100, 'Galway'), ('en_US', 1101, 'Kerry'), ('en_US', 1102, 'Kildare'), ('en_US', 1103, 'Kilkenny'), ('en_US', 1104, 'Leitrim'), ('en_US', 1105, 'Leix'), ('en_US', 1106, 'Limerick'), ('en_US', 1107, 'Longford'), ('en_US', 1108, 'Louth'), ('en_US', 1109, 'Mayo'), ('en_US', 1110, 'Meath'), ('en_US', 1111, 'Monaghan'), ('en_US', 1112, 'Offaly'), ('en_US', 1113, 'Roscommon'), ('en_US', 1114, 'Sligo'), ('en_US', 1115, 'Tipperary'), ('en_US', 1116, 'Waterford'), ('en_US', 1117, 'Westmeath'), ('en_US', 1118, 'Wexford'), ('en_US', 1119, 'Wicklow');