One-A in Illinois is schools with a population of one student or fewer.
Actually Illini Central is the former Mason City High in Mason City, IL (pop. 2700, mebbe). The D-blog was incarcerated there in the mid-70s. It was consolidated with a couple of even tinier towns, San Jose (San JOES) and Easton (EAston), some years back.
Always had something of a sketchy relationship with Mason City, but, cool. Here's the State Journal Register's story.