I'm having difficulties following your description …
What does “select a state” mean? Are you constraining / filtering the list by that selection? Or navigating to a state within the list?
If it is the former, and you're only displaying attendees from a single state, you neither need to sort the records by state (it's the same state, after all), nor do you need a summary field; you can insert the symbol for FoundCount.
If you're actually displaying records for several states, then you probably need a sub-summary part with State as the break field; place the state name and the summary field into that part to get a group count (i.e. by State).
Be aware that now you must sort by state – i.e. the part's break field – or the part won't appear.