That is kind of a myth. A town of 2000 people may fill a stadium that seats 1500 but a town of 500,000 people will l have a lot of old folk in it sure but could probably fill a stadium that seats 40K. The numbers for the state finals were the highest when they were in Miami... Compare them to Gainseville and Tallahassee (Tallahassee had local teams playing in title games those years too).
As for the last time they held the games in Miami (2006), the 8A state championship game had Miami Northwestern as they were starting their historic run. Additionally, other games that year had a 3rd installment of Lakeland and STA (as Lakeland was looking for a 3 peat). Additionally, Muck City showed out as Glades Central, Pahokee, Clewiston, and Glades Day all were playing in the first weekend of games.
Additionally only Pine Forest, Bolles, North Central Florida, and FAMU came from N of Orlando. 2 of those played in the smallest classes and are not going to bring large numbers no matter the location of the games.
Basically, what I am saying is 2006 was the perfect mix of teams to produce a historic numbers in terms of attendance.
In 2005, they had attendance of 36K, still a good number though, but the games were held in Gainesville the year before and they had 31K and they had one less classification.
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While I think playing in a stadium like the Citrus Bowl or in Daytona Beach will always be an awesome experience for a high schooler and the community they represent, I hope one day they move the 1A state championships to Gainesville (Citizen's Field) or Lake City or Tallahassee (Cox Stadium). I hope one day 2A is played at the home stadium of one of the football teams. I know the FHSAA won't do this because it cedes too much control and is not equitable to the small schools, but it makes more sense