gistfile1.phtml

add_action('add_meta_boxes', 'gov_meta_box_add');
function gov_meta_box_add()
{
    add_meta_box('post-meta-box-id', 'Event Type', 'gov_meta_box_cb', 'post', 'side', 'high');
    add_meta_box('page-meta-box-id', 'Event Type', 'gov_meta_box_cb', 'page', 'side', 'high');
}

function gov_meta_box_cb($post)
{
    $values   = get_post_custom($post->ID); // error_log(json_encode($values));
    $selected = isset($values['gov_event_type']) ? esc_attr($values['gov_event_type'][0]) : '';
    wp_nonce_field('gov_meta_box_nonce', 'gov_meta_box_nonce');
    ?>
    <p>
        <label for="my_meta_box_select">Please select type:</label>
        <select name="gov_event_type" id="sel-gov_event_type">
            <option value="">--</option>
            <option value="month" <?php selected($selected, 'month'); ?>>Month</option>
            <option value="week" <?php selected($selected, 'week'); ?>>Week</option>
            <option value="day" <?php selected($selected, 'day'); ?>>Day</option>
        </select>
    </p>
<?php
}

add_action('save_post', 'gov_meta_box_save');
function gov_meta_box_save($post_id)
{
    // Bail if we're doing an auto save
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) return;

    // if our nonce isn't there, or we can't verify it, bail
    if (!isset($_POST['gov_meta_box_nonce']) || !wp_verify_nonce($_POST['gov_meta_box_nonce'], 'gov_meta_box_nonce')) return;

    // if our current user can't edit this post, bail
    if (!current_user_can('edit_post')) return;

    if (isset($_POST['gov_event_type']) && $_POST['gov_event_type']) {
        update_post_meta($post_id, 'gov_event_type', esc_attr($_POST['gov_event_type']));
//    update_post_meta( $post_id, 'gove_event_month', )
    }
}