Several reasons for the change.
We tried to look at east coast school schedules, and it seemed like we were clear with that late of a June date.
The drivers for the change were the school schedule / availability, and the timing of re-finishing the gym floors. The re-finishing happens during ISHAA Moratorium Week (the week of July that includes July 4). This is a time consuming and expensive process. With our old date, we were usually the first group on the new floor. And, 2 of the past 3 years there has been floor damage (not from the playing field, but from the queuing areas). And we had a very close call again this year. If we had to pay to redo the floor refinishing we could not afford to host to host the event.
So by moving to late June, we are the last group on the floor before it is re-finished. We still need to be careful, but there is less risk to us.