NumbersUSA has a useful August Recess Town Hall Map, and they write:
The primetime for political activism is here: August Recess. NumbersUSA is ready to provide you the most up-to-date information on town hall meetings with your members of Congress. All concerned Americans are encouraged to use our new August Recess Town Hall Map to find local events at which to hold elected officials accountable.
If you are not a concerned American, but are rather a concerned Mexican, El Salvadoran, or Guatemalan, do not show up at these town halls.
The place to show up to hold your elected officials accountable is either Mexico City, San Salvador, or Guatemala City.