At the top level there has been consolidation to form power conferences. In NW there was the Toledo City league which had played for 90 years but competitive disparaties began to emerge between the affluent catholic schools and the public schools in the 70's. In 2010 the decision was made by the catholic schools that it was time to put together a power conference with the big publics in the area Oregon, Fremont, Findlay, Lima plus the largest public school in the city league Whitmer. 10 school conference and since that time not a deletion or addition to it because its the best possible conference for everyone involved. It reminds me of the ACC with all the private schools in it plus a few big outlier public schools. Lima is the Florida State of the conference as a traditional elite football power. They aren't technically in NW Ohio but because they are on I-75 which is the lifeblood of NW Ohio they can conveniently hop on a bus and be in the Toledo metro within an hour. Findlay is the Louisville of the conference which had played in many leagues over the years as a dominant basketball school with mediocre football. They were in CUSA type conferences until the 90's when they joined the Great Lakes League which was like a Big East with most of the significant NW Ohio D1 & D2 non city league schools in it. Of course with Findlay's arrival to a conference that was always the cue for the weaker D2 schools to exit stage left for fear of Findlay basketball and Olympic sports. The last incarnation of the GLL was the Greater Buckeye League with Findlay, Fremont, Lima, Marion, Napoleon and Sandusky from 2003-2011. Napoleon was a smaller school that always punched above its weight in athletics because of the strong community based area. Sandusky had enrollment declines so they dropped to the mid major Sandusky Bay conference. Marion is in the more regional mid-ohio athletic conference. The city schools of the industrial towns have tended in recent years to move down to mid major leagues to save on travel. The wealthy growing suburban type schools have moved up to be more competitive. Findlay's historical situation is different as it benefited in the new economy as a logistics hub and has tripled in size since WWII. For this reason its more similar to a Columbus suburb and they usually put Dublin or one the other big suburban Columbus schools on the schedule since the 90's to maximize playoff points. The answer is it depends on institutional objectives but there is natural hierarchy that exists. Lima Senior, Findlay and Toledo Whitmer are never going to back down from elite D1 competition. They would play independent (which they did) before that happens.
Three Rivers
https://en.wikipedia.org/wiki/Three_Rivers_Athletic_Confe... Greater Buckeye
https://en.wikipedia.org/wiki/Greater_Buckeye_ConferenceSlight correction. Whitmer, while located in the city of Toledo, is not a Toledo Public School. It is part of its own separate school district, Washington Local Schools. So now all that remains of the Toledo City League is all of the public schools, which for the most part, are not very competitive in much of anything anymore. My dad played basketball at Woodward in the early 60s. Woodward had some awesome teams back then. I can't imagine it ever being the case again.
Marion Harding is an interesting case. It ended up joining the MOAC after the Greater Buckeye Conference folded. It is by far the biggest school in the MOAC but competitively and geographically, the MOAC is a good fit for the Presidents, which really haven't been able to compete against most Division I schools for a while now. It has a lot of the same struggles as some inner-city schools with low participation.
I went to Clay and played in the former Great Lakes League. My alma mater doesn't seem to compete very well at much in the Three Rivers League, which is a lot of the former GLL plus the Toledo Catholic schools. I'm pretty sure Clay is the smallest school in the league now, with the exception of perhaps Toledo Central Catholic, but obviously it has the advantage of being a private school attracting students from a large area. (For example, former Ohio Bobcat and NFL player Eric Herman lived in the Clay district but went to Central Catholic). I don't know if Clay would ever leave its current league but after a while, schools start to hate losing in a league over and over, especially if they are one of the smaller schools in that conference.
It seems most of the Northwest Ohio conference realignment should be done for the most part. One of the biggest things that happened was the Northern Ohio League, which was one of the longest-lasting leagues in Ohio, dating back to the early 40s, disbanded with most of the teams joining the Sandusky Bay Conference, which has 20-plus teams in three divisions broken down by size. Hopewell-Loudon is leaving the 12-team Blanchard Valley Conferences for the SBC, so that could lead to the BVC perhaps seeking a replacement. The Northern 10 Athletic Conference had Crestline leave the league after just the first season, and so now has only nine teams, but Ridgedale has opted to play independently for football, so I think the N10 is satisfied being an eight-team football league. The odd number of teams isn't as big a deal for other sports.
It certainly is interesting how just one move can create a domino effect.