In California, there are 10 CIF sections: Southern, San Diego, Los Angeles, Central, Central Coast, Oakland, San Francisco, Sac-Joaquin, Northern, North Coast.
My section, the CIF-Southern Section, is the largest in both number of schools with 585 schools and land area covering about 1/3 of the the state and nearly half its population. It covers the counties of Orange, Los Angeles (including all private schools in the LAUSD section area), Riverside, San Bernardino, Ventura, Santa Barbara, San Luis Obispo, Mono, Inyo and a bit of Kern. The thing is a monster.
In football, the section is divided into 13 divisions. Until recently, the divisions were sort of geographic, sort of by school size, sort of public/private, sort of by team quality. It's something that was always tinkered with trying to get the right teams in the right place based on all those things. At one point, they went from numbered divisions (1,2,3, etc) to naming them (Pac-5, East Valley, Southwest Valley, etc.), but the names were dumb and didn't mean really mean anything to anybody (it happened while I was in school, and we all assumed it was to make us not feel bad as a Division 9 team playing Division 2 teams or whatever). Teams from along the ocean were playing in the East Valley division, for example, but all that division really was was the small schools division.
Anyway, that all changed two years ago when the CIF-SS instituted a new point-based system to improve competitive equity. They reinstated the 13 numbered divisions and placed teams based on a formula of wins, playoff wins, championships, strength of schedule, among others. Has it worked? Yes and no. Some divisions are extremely competitive, others have anomalies where teams started in a lower division than they should've, cruised to a title last season, and are in a proper division this season.
Because of the existing league and playoff structures, some teams have been royally screwed. In the past, 5/6 team leagues had three automatic playoff qualifying spots and because those leagues were assigned to specific playoff divisions, the teams would just be seeded accordingly. Now the competitive equity has thrown all the teams into the wind. You might have a league champion who wins the league every single season and because of that they're in Division 2, then the 2nd and 3rd place team may be in like Division 7 or Division 13.
Well here's the thing, the top two divisions each have only 18 teams, and each division has 16 playoff spots. So if you're lucky enough to be in those top two divisions, congrats, unless you crap the bed, you're at least making the playoffs. But that 2nd or 3rd place team that gets thrown into the lower division mix, well, Division 7 has 23 schools (not too bad) but Division 13 has 84 schools. And when you get to playoff seeding, league champs are put into the bracket first, 2nd place after (if there's room), 3rd place (if there's still room) and even wild cards (usually just in the top few divisions). Last season and maybe even this season again, we had teams ranked in the top 10 of their respective divisions polls all season, but ended up in 3rd place in their league because they might have a Division 2 league champ and maybe a Division 4 second place team, but couldn't make the playoffs in a lower division, because they got squeezed out.
Anyways, to the nuts and bolts.
13 playoff divisions in the CIF-SS
16 playoff teams per division
All championship games except Division 1 are played at the higher-seeded school or site selected by the school
Division 1 title game is played at Angel Stadium
All 52 Section Division champions (26 north, 26 south) are then slotted into 13 respective divisions (based on the competitive equity mentioned earlier) into state regional games (aka, state semifinals, north and south)
There are 13 state championship divisions
Open Division (THE State Championship. Any team can be selected. Although, in the North its always De La Salle of Concord.)
Divisions 1-6, with AA and A designations.
Open Division, Divisions 1AA, 1A, 2AA, 2A compete at Sacramento State. All other divisions are at home sites.
Also, State Championships in California were only reinstated relatively recently. State championships were "awarded" between 1915 - 1917, then actually competed for from 1919-1927, when they were discontinued due to concerns of the length of the season and financial issues and scheduling, etc. Before their revival, California was the only state without a state title game. State championships were revived in 2006 as State Bowl Games where committees selected a SoCal team and a NorCal team for 3 divisions, which expanded to 5 divisions in 2008. In 2012, the regional games were added, and in 2015, it was expanded so that all 52 different section division champions will compete in the regional games to advance to the state title.
Funnily enough as the first championship games were stopped after length of season concerns, we still have that concern now with all the expansion. If a team goes all the way to the state title game, with a 10 game regular season, 4 game section playoff, 2 game state playoff, that's 16 games for a high school team competing from the last weekend in August to the middle of December. Even the best college teams will play 15 at the most (assuming conference title game and two playoff games), and they have a month+ break between the final two. Many high school teams are lucky if they can even schedule a bye week now (many schools opting to start in "Week 0" to get a bye week before league play). It's just a lot.
Anyways, thanks for indulging in my soliloquy on California high school football. There's a lot to it lol.