This snippet adds UK postal counties to WooCommerce’s list of states.

Add this code to your child theme’s functions.php file or via a plugin that allows custom functions to be added, such as the Dessky Snippets plugin. Please don’t add custom code directly to your parent theme’s functions.php file as this will be overwritten completely when you update the theme.

function  wc_uk_counties_add_counties( $states ) {

    $states['GB'] = array(
                            'AV' => 'Avon',
                            'BE' => 'Bedfordshire',
                            'BK' => 'Berkshire',
                            'BU' => 'Buckinghamshire',
                            'CA' => 'Cambridgeshire',
                            'CH' => 'Cheshire',
                            'CL' => 'Cleveland',
                            'CO' => 'Cornwall',
                            'CD' => 'County Durham',
                            'CU' => 'Cumbria',
                            'DE' => 'Derbyshire',
                            'DV' => 'Devon',
                            'DO' => 'Dorset',
                            'ES' => 'East Sussex',
                            'EX' => 'Essex',
                            'GL' => 'Gloucestershire',
                            'HA' => 'Hampshire',
                            'HE' => 'Herefordshire',
                            'HT' => 'Hertfordshire',
                            'IW' => 'Isle of Wight',
                            'KE' => 'Kent',
                            'LA' => 'Lancashire',
                            'LE' => 'Leicestershire',
                            'LI' => 'Lincolnshire',
                            'LO' => 'London',
                            'ME' => 'Merseyside',
                            'MI' => 'Middlesex',
                            'NO' => 'Norfolk',
                            'NH' => 'North Humberside',
                            'NY' => 'North Yorkshire',
                            'NS' => 'Northamptonshire',
                            'NL' => 'Northumberland',
                            'NT' => 'Nottinghamshire',
                            'OX' => 'Oxfordshire',
                            'SH' => 'Shropshire',
                            'SO' => 'Somerset',
                            'SM' => 'South Humberside',
                            'SY' => 'South Yorkshire',
                            'SF' => 'Staffordshire',
                            'SU' => 'Suffolk',
                            'SR' => 'Surrey',
                            'TW' => 'Tyne and Wear',
                            'WA' => 'Warwickshire',
                            'WM' => 'West Midlands',
                            'WS' => 'West Sussex',
                            'WY' => 'West Yorkshire',
                            'WI' => 'Wiltshire',
                            'WO' => 'Worcestershire',
                            'ABD' => 'Scotland / Aberdeenshire',
                            'ANS' => 'Scotland / Angus',
                            'ARL' => 'Scotland / Argyle & Bute',
                            'AYR' => 'Scotland / Ayrshire',
                            'CLK' => 'Scotland / Clackmannanshire',
                            'DGY' => 'Scotland / Dumfries & Galloway',
                            'DNB' => 'Scotland / Dunbartonshire',
                            'DDE' => 'Scotland / Dundee',
                            'ELN' => 'Scotland / East Lothian',
                            'EDB' => 'Scotland / Edinburgh',
                            'FIF' => 'Scotland / Fife',
                            'GGW' => 'Scotland / Glasgow',
                            'HLD' => 'Scotland / Highland',
                            'LKS' => 'Scotland / Lanarkshire',
                            'MLN' => 'Scotland / Midlothian',
                            'MOR' => 'Scotland / Moray',
                            'OKI' => 'Scotland / Orkney',
                            'PER' => 'Scotland / Perth and Kinross',
                            'RFW' => 'Scotland / Renfrewshire',
                            'SB' => 'Scotland / Scottish Borders',
                            'SHI' => 'Scotland / Shetland Isles',
                            'STI' => 'Scotland / Stirling',
                            'WLN' => 'Scotland / West Lothian',
                            'WIS' => 'Scotland / Western Isles',
                            'AGY' => 'Wales / Anglesey',
                            'GNT' => 'Wales / Blaenau Gwent',
                            'CP' => 'Wales / Caerphilly',
                            'CF' => 'Wales / Cardiff',
                            'CAE' => 'Wales / Carmarthenshire',
                            'CR' => 'Wales / Ceredigion',
                            'CW' => 'Wales / Conwy',
                            'DEN' => 'Wales / Denbighshire',
                            'FLN' => 'Wales / Flintshire',
                            'GLA' => 'Wales / Glamorgan',
                            'GWN' => 'Wales / Gwynedd',
                            'MT' => 'Wales / Merthyr Tydfil',
                            'MON' => 'Wales / Monmouthshire',
                            'PT' => 'Wales / Neath Port Talbot',
                            'NP' => 'Wales / Newport',
                            'PEM' => 'Wales / Pembrokeshire',
                            'POW' => 'Wales / Powys',
                            'RT' => 'Wales / Rhondda Cynon Taff',
                            'SS' => 'Wales / Swansea',
                            'TF' => 'Wales / Torfaen',
                            'WX' => 'Wales / Wrexham',
                            'ANT' => 'Northern Ireland / County Antrim',
                            'ARM' => 'Northern Ireland / County Armagh',
                            'DOW' => 'Northern Ireland / County Down',
                            'FER' => 'Northern Ireland / County Fermanagh',
                            'LDY' => 'Northern Ireland / County Londonderry',
                            'TYR' => 'Northern Ireland / County Tyrone',
                           );
    return $states;

}

add_filter( 'woocommerce_states', 'wc_uk_counties_add_counties' );