Because of AP blackouts, the 4th of July really isn't too bad, especially in the mornings where the park is close to a ghost town. However, toward the late afternoon and evening, the masses can descend on the park and it can get packed.
Our most memorable time at Disneyland was July 4, 1976. You guys can guess why, correct? There were T O N S !!! of people, but not a single stroller-in-the -back-of-the-ankle problem and absolutely no negative vibrations.
However, toward the late afternoon and evening, the masses can descend on the park and it can get packed.
^^^ It really is the evening that is the problem as people show up then to wait for the biggest firework show of the year.
Compared to this week in the Christmas season, the 4th doesn't look bad. It is very busy but when it falls midweek like it will this year, it doesn't get insane like it can when it fall on Fri-Mon, making a three days weekend that draws more people there.