alt Hacker NewsI gave up throwing parties after the first two years in the States (1998-2000)
Americans throughout treat RSVPs as meaningless, show up if they feel like it, and think it's fine to cancel plans five minutes before the scheduled start.
Unless you're a glutton for punishment, you take the hint at some point.
I remember a pot luck dinner where I was the only guest that brought food. The invitation was clear, just ignored.