There is of course a document with the details. The quick answer a "core committee" starts the ball rolling. The "core committee" is responsible for sorting out a venue, selecting a logistical organizer and electing a conference chair. This is where the collaboration comes in as the "core committee" is made up of an OSGeo representative (Marc Lucas), LocationTech representative (Jim Hughes) along with three prior conference chairs (for continuity).
The "core committee" selects a venue by RFP, inviting venues to respond, shortlisting results, and reviewing the top locations reviewed in person. This year it was a tight race between a bid from Philadelphia (which ended up being too small) and from Raleigh, where the event was held.
The final question is who runs the event? This time it is a conference committee, headed up by Andrea Ross who was elected conference chair. Responsibilities were divided up with Andrea rounding up all the behind the scenes work as producer (made exciting by responding to HB2). Rob Emanuele acted as program chair pulling together public feedback, balancing the program and the all important scheduling. Sarah Cordivano volunteered as community chair leading the proceedings as spokesperson for the event.
A big thanks to the organizers of FOSS4G-NA 2016 for your hard work, and thank you for the great event!