We will be playing my town's July 4th celebration, on a main stage in the biggest park in the entire town. Every year it fills COMPLETELY (we're talking probably at least 1,000 people) to watch the fireworks at the end of the night, and a band plays from about 5:30 until 9PM, when the fireworks start. My band has the opening slot, so we will play to a few hundred, but still....we are SO pumped! Here is a shot of the crowd during last year's opener:
As you can see, the place is just about full to that first fence-barrier.
And here is a shot of the entire park we'll be playing to, which will gradually be overtaken by people throughout the length of our setlist:

The red box is our stage, and the blue circle shows how dense the crowd will be by 9PM. Hopefully we get a good chunk of that in the first few hours!!