Although the headline of this story is, "Killington outbreak is not widespread," on September 4 the Vermont Health Department (@healthvermont on Twitter) reported "Currently 17 associated cases. Of those, 11 attended the private party; 6 others are due to subsequent transmission from an attendee." This was a relatively large outbreak for Vermont whose levels had been very low prior to this. Other news outlets, such as VPR, reported it as a significant outbreak:
https://www.vpr.org/post/killington-party-center-new-covid-19-outbreak#stream/0