None of the examples using jquery in here are actually correct as they will leave the select displaying the first entry even though value has been changed.
The right way to select Alaska and have the select show the right item as selected using:
<select id="state">
<option value="AL">Alabama</option>
<option value="AK">Alaska</option>
<option value="AZ">Arizona</option>
</select>
With jquery would be:
$('#state').val('AK').change();