How do I have the form stay on the select value when I go back to the page?

Website: http://redoxstudio.us/a2zcolleges/Un...choolsUSA.html

For example, if I select Florida in the drop down form (under Select a State) the page goes to the Florida page. When I go back to the page with the forms it is still on Florida and not Alabama.

Here is the code for the form -

<form action="" method="post" name="states" id="states">
<strong class="text12Point">Select a State</strong><br />
<select onchange="window.open(this.options[this.selectedIndex].value,'_top')" name="" style="width: 150px; height: 25px; font-size: 14px; background-color: #fabc71; font-family: Times New Roman;" >

<option selected="selected" value="http://www.a2zcolleges.com/undergrad/alabama.html">Alabama</option>
<option value="http://www.a2zcolleges.com/undergrad/alaska.html">Alaska</option>
<option value="http://www.a2zcolleges.com/undergrad/arizona.html">Arizona</option>

Thanks,
Bob