Sell in Specific States/Provinces/Regions with WooCommerce

functions.php

<?php
/**
* @template      Sell to Specific States/Provinces/Regions with WooCommerce
* @author        Nicola Mustone
* @author_url    https://nicolamustone.blog/2014/12/08/sell-in-specific-states-with-woocommerce/
* @tested-up-to  WooCommerce 8.4.X
*/
function wc_sell_only_states( $states ) {
	$states['US'] = array(
		'CA' => __( 'California', 'woocommerce' ),
	);

	return $states;
}
add_filter( 'woocommerce_states', 'wc_sell_only_states' );