client-side / server-side question

[Jake]

To avoid a postback, we want to use a webservice and XMLHTTP to fetch the
list of values for dropdowns whose contents are determined by an earlier
user-choice on the page. E.g. if the user selects "FL" from the State
dropdown, the Cities dropdown will be populated with cities in Florida only:

State Dropdown Cities Dropdown
NY Miami
PA Tampa
FL St Augustine


If the Cities dropdown is a client-side SELECT object populated in this
manner (i.e. client-side DOM parsing of XML dataset returned by a
webservice), is it possible, in code-behind, to detect which City was
selected?

Thanks
Jake