How to add a US State dropdown field

To add a dropdown field that contains the US States, first add a new dropdown field to a field group and edit the 'Unique meta key' setting to  field_us_state.

Then create a new file 'wpum-field-state.php' in wp-content/mu-plugins (you might need to create the directory), and copy and paste the following code:

<?php

add_filter( 'get_wpum_field_metadata', 'my_wpum_state_data', 10, 3 );

function my_wpum_state_data ( $check, $object_id, $meta_key ) {
	if ( 'dropdown_options' !== $meta_key ) {
		return $check;
	}

	$user_meta_key = WPUM()->field_meta->get_meta( $object_id, 'user_meta_key', true );
	if ( $user_meta_key !== 'wpum_field_us_state' ) {
		return $check;
	}

	$states = array(
		'AL' => 'Alabama',
		'AK' => 'Alaska',
		'AZ' => 'Arizona',
		'AR' => 'Arkansas',
		'CA' => 'California',
		'CO' => 'Colorado',
		'CT' => 'Connecticut',
		'DE' => 'Delaware',
		'DC' => 'District Of Columbia',
		'FL' => 'Florida',
		'GA' => 'Georgia',
		'HI' => 'Hawaii',
		'ID' => 'Idaho',
		'IL' => 'Illinois',
		'IN' => 'Indiana',
		'IA' => 'Iowa',
		'KS' => 'Kansas',
		'KY' => 'Kentucky',
		'LA' => 'Louisiana',
		'ME' => 'Maine',
		'MD' => 'Maryland',
		'MA' => 'Massachusetts',
		'MI' => 'Michigan',
		'MN' => 'Minnesota',
		'MS' => 'Mississippi',
		'MO' => 'Missouri',
		'MT' => 'Montana',
		'NE' => 'Nebraska',
		'NV' => 'Nevada',
		'NH' => 'New Hampshire',
		'NJ' => 'New Jersey',
		'NM' => 'New Mexico',
		'NY' => 'New York',
		'NC' => 'North Carolina',
		'ND' => 'North Dakota',
		'OH' => 'Ohio',
		'OK' => 'Oklahoma',
		'OR' => 'Oregon',
		'PA' => 'Pennsylvania',
		'RI' => 'Rhode Island',
		'SC' => 'South Carolina',
		'SD' => 'South Dakota',
		'TN' => 'Tennessee',
		'TX' => 'Texas',
		'UT' => 'Utah',
		'VT' => 'Vermont',
		'VA' => 'Virginia',
		'WA' => 'Washington',
		'WV' => 'West Virginia',
		'WI' => 'Wisconsin',
		'WY' => 'Wyoming',
	);

	$data = array();
	foreach ( $states as $state_abbrev => $state ) {
		$data[] = array( 'value' => $state_abbrev, 'label' => $state );
	}

	return array( $data );
}