People discount this, but here's the main reasons it was crazy on Juneteenth this year.
1. There were two Pride nights the Monday and Wednesday of the same week, with Juneteenth on Thursday. Any time one of the parks closes early for a special event, it completely messes up crowds at the parks for the entire week. The Sunday and Tuesday of the same week were completely empty at the parks. People shifted visits to the Thursday - weekend period to gain longer hours and all the nighttime entertainment. This is even more pronounced than normal right now because of PTN being offered PLUS the regular stuff. Pride Nights being at DL obviously meant no PTN, Fantasmic or fireworks for regular park guests. Why pay for a full day ticket or use one of your multiday tickets when DL closes early and you can't see nighttime entertainment?
2. Believe Keys (the second highest level) were not blocked. This is a lower impact, but a factor.
3. Single day ticket prices were $180, which is high, but lower than the $196 or $206 you saw over July 4th weekend. The lower the single day price = the higher the crowds. Usually the crazy crowds come out when the price is below $150, so this variable is a bit more perplexing to me (likely offset by the 70th and Costco ticket deals).
It is not automatically true that federal holidays = crowded. Actually, it's often the opposite. The single day ticket prices, MK blockouts, plus special event calendar is the most telling. Many "other" federal holidays such as Memorial Day or July 4th come with higher single day ticket prices.
I was there July 4th weekend this year and last year - crowds were very light both years. Personally, I avoid the fall because of all the early DCA closures due to OBB. Even on non-OBB days it really impacts crowd flow at the resort because people are shifting visits to avoid the early closure at DCA.
Putting some kind of objective data to my arguments, look at the TP crowd calendar for 7/6 (a Sunday with ticket prices at $196) vs. 7/8 (a Tuesday with ticket prices at $164). Look TP is not perfect, and they base predictions on only wait times, but it is some kind of data point. Sunday was considerably less crowded than Tuesday under otherwise similar conditions and the same MK blockouts. The weather was actually hotter Tuesday, so you'd expect less crowds.
