Richer Yang

This plubin is based on <a href="https://tw.wordpress.org/plugins/wc-city-select/" rel="nofollow ugc">WC City Select</a>
WooCommerce uses a text input for the customers to enter the city or town. 
With this plugin you can provide a list of cities to be shown as a select dropdown.
This will be shown in checkout pages, edit addresses pages and shipping calculator if it’s configured that way.
After selected the city or town, auto set the postcode number if is defined.
<h3>How to add cities</h3>
A list of cities can be added in your theme functions.php file.
Use <code>ry_wc_city_select_cities</code> filter to load your cities. 
This is done similarly to <a href="https://docs.woocommerce.com/document/addmodify-states/" rel="nofollow ugc">Add/Modify States</a>. 
It should be added on your functions.php or a custom plugin.
<pre><code>add_filter( 'ry_wc_city_select_cities', 'my_cities' );
/**
 * Replace XX with the country code. Instead of YYY, ZZZ use actual state codes.
 * The City list can list of city name with postcode or just city name.
 */
function my_cities( $cities ) {
 $cities['XX'] = array(
 'YYY' => array( // city name with postcoe
 ['City', '100'],
 ['Another City', '101']
 ),
 'ZZZ' => array( // just city name
 'City 3',
 'City 4'
 )
 );
 return $cities;
}
</code></pre>

RY City Select for WooCommerce

Show a dropdown select as the cities input on WooCommerce. Auto set the postcode for selected city.

WordPress Monsters

Plugin contains American zip code database. You can activate this plugin for any post type in settings. After activation you can set zip codes for all of your posts. To connect zip code with the post you should do only 3 steps: 1) Choose State ( then the plugin will display all available cities in the chosen state) 2) Choose City ( then you will see all available Zip codes in this city) 
3) Choose Zip code. Also you can connect several zip codes to one post. Use ID, ‘zipFields’, true ); ?>to get an array of connected zip codes.

USA Zip Codes by WP Monsters

Choose USA zip codes for your post types.

RY City Select for WooCommerce vs USA Zip Codes by WP Monsters