how to make URL link query string

This is how I got it working:

ADDED this to functions.php:

function include_template_function( $template_path ) {
    global $wp;
    if ($wp->request == 'state') {
        $template_path = locate_template( array ( 'state.php' ) );
    }
    return $template_path;
}

$state_name = $_GET['st']; //this is added to use as a global variable

ADDED THIS to header.php because WP thinks it’s serving a 404 page

    if ($wp->request == 'state') { 
        echo 'Member Centers in ' . $state_name . ' | ';
    } else {
        wp_title( '|', true, 'right' );
    } 
?>
</title>

ADDED THIS to the base template (page.php):

<?php 
    $baseURL = esc_url( home_url( "https://wordpress.stackexchange.com/" ) );
    $ak_link = $baseURL . 'state?st=Alaska'; // for each state
?>
<a href="https://wordpress.stackexchange.com/questions/124326/<?php echo $ak_link; ?>">Show Alaska Pages</a> 

CREATED state.php template that handles state queries:

<?php global $state_name; ?> ?>

<?php 
    $mypages = get_pages('child_of=".$parent_page_id."&sort_order=ASC&parent=".$parent_page_id."&meta_key=ctr_state&meta_value=".$state_name);
    foreach($mypages as $page)
    {
?>
... Do Stuff! ...
<?php } ?>