How to Set WordPress Dashboard to Use One Column

one-column-dashboard

function screen_layout_columns( $columns ) {

	$columns['dashboard'] = 1;

	return $columns;

}

add_filter( 'screen_layout_columns', 'screen_layout_columns' );

function screen_layout_dashboard() {

	return 1;

}

add_filter( 'get_user_option_screen_layout_dashboard', 'screen_layout_dashboard' );