function toggleLayer(whichLayer) {
	var element;
	for (var i = 1; i <= 3; ++i) {
		element = document.getElementById('states' + parseInt(i));		
		element.className = (i == whichLayer ? 'states_show' : 'states_hide');
		element = document.getElementById('link' + parseInt(i));		
		element.className = (i == whichLayer ? 'link_show' : 'link_hide');
	}
}