I'll preface this by saying I am not from Missouri and I do not know all the ins and outs of y'alls system; however my current understanding is that there isn't a class 6A in Missouri music festivals. It doesn't exist. Per the MSHSAA (which seems to be Missouri's governing body for sports/activities), there's only class 1A through 5A for music activities. While sports like football might have the additional class 6A, music does not. Thus, 5A is the largest class. I believe that answers your question, but we do have a handful of Missouri folks on here who can certainly add more context.
And for inquiring minds -- these classes are based on school enrollment (ugh) in grades 9-11.
5A = 988 & above
4A = 464 - 987
3A = 208 - 463
2A = 100 - 207
1A = 99 & below
*numbers for the 19-20 AY
Yeah, here in Missouri, the idea of a 6A division is just kind of a joke because it's never existed. In my opinion, this part of Missouri doesn't even have any schools that are big enough or that are at a high enough level to be considered 6A, though we do have a few close candidates. I assume you are referring to Broken Arrow when you question the 6A choir. The thing is, Broken Arrow is from out of state and we almost never see them. Groups like Broken Arrow rarely come to this area to compete, so our comps have never decided to assign a 6A division, especially if they are run by MSHSAA guidelines. They are placed into our 5A division as a result which as you can see happened here. I checked OSSAA's (Oklahoma's equivalent for MSHSAA) website and they actually don't have a 1A for choir, so is it possible that the states just use different titles for equivalent school sizes? Although, their guidelines for divisioning are also very different so honestly it's hard to compare anything fairly. I just know that it wouldn't have been fair to put Broken Arrow in their own 6A division because then they'd be competing by themselves and they're just way too good to do that to them. I think placing amazing groups like Broken Arrow in 5A is fine because it only motivates our area's top groups (Neosho, Carthage, Joplin) to step up their game.
My school was just upgraded from 4A to 5A this year due to a boost in student population. Our area has gathered more 5A choirs due to higher populations, so maybe MSHSAA will add a 6A division for choir at some point in the future. But until then, groups like BA will have to compete with us in our 5A division if they want to compete in Missouri.
Single-Gender Division
1st Place: Oliver Tiger Fire
Captions
Best Ballad: Carthage Sound Machine
Best Male Soloist: Collier Hendrickson from Neosho Wildcat Singers
Best Female Soloist: Anne Marie Wright from Webb City Polyphonics
Best Choreography: Webb City Polyphonics
Best Vocals: Carthage Sound Machine
One correction: In the prep division, currently listed is "Vocal Velocity (Smith-Cotton High School)" this should be "Velocity (Mt. Vernon High School)". Additionally, here is Friday night's junior high competition schedule:
6:00 p.m. - Webb City Junior High School "Euphonics" (Mixed)
6:25 p.m. - Neosho Junior High School "Wildcat Singers" (Mixed)
6:50 p.m. - Oliver Middle School "Tiger Genesis" (Mixed)
7:15 p.m. - Carthage Junior High School "Sound Machine" (Mixed)
7:40 p.m. - Nevada Middle School "Future Sounds" (Mixed)
8:05 p.m. - Webb City Junior High School "Polyphonics" (Mixed)
8:30 p.m. - Oliver Middle School "Tiger Fire" (Single-Gender)
The Broken Arrow performance groups are mixed on the version on this page, it should be:
8:55 a.m. - Broken Arrow Freshman Academy "Tiger Momentum"
1:15 p.m. - Broken Arrow High School "Tiger Rhythm"
3:20 p.m. - Broken Arrow High School "Tiger Mystique"
All updated. Truthfully, I blame the Joplin schedule for being all over the place with performance times for all these divisions. In reality, I knew Broken Arrow adjusted the times among their groups and I misinterpreted which groups actually swapped. Appreciate the corrections!
In reality, I knew Broken Arrow adjusted the times among their groups and I misinterpreted which groups actually swapped. Appreciate the corrections! 
