In the U.S., we commonly say someone serves “on” the school board, zoning board or city council, but “in” the state house or state senate, or in either house of Congress. Is the distinction a function of the size of the institution, its power, or something else?
Size of the body, perhaps? Typically municipal boards don’t exceed a dozen members, with 3-6 being normal in my experience. Legislatuires, including Congress, tend to be much larger groups. (This is purely speculative, based on my “ear” for usage matching your own.)
Moderator’s Note: Although this thread was started on the Great Debates forum, I think it would work better in General Questions.
Similarly, how did the usage of “on” and “in” as they relate to TV and movies start? Almost invariably, we say “He was on ‘How I Met Your Mother’” but “He was in ‘Dirty Harry’”. Why “on” for TV shows but “in” for movies?
Or, even more to the point, “Alan Alda was on ‘MASH’", but "Elliott Gould was in 'MASH’”.
I’d say it’s the difference between a board of councilmen and the body of legislators.
Some things about language just defy a rationale explanation. There was no committee who made the decision at a specific point in time. Another similar example is how we go “to the store” but just “to church.” In the US we say someone is “in the hospital” but in the UK they say “in hospital.”
In New York City people stand “on line” but in the rest of the country they stand “in line.”
Prepositions, in all languages from what I understand, are especially subject to idiosyncrasies of usage. Trying to translate a preposition from a language one is learning can be an exercise in misery. Look one up in a translation dictionary and half a dozen English equivalents may be cited.
I checked my usage guides and didn’t find anything on this, although Partridge has a long section on “prepositions incorrectly used” which is the same thing as saying that people in casual speech will choose a preposition that makes sense to them without checking with the “authorities.”
Size may be the issue in this particular case. Length of service may be another. (You’d serve on a board temporarily but in a position for a longer term.) That’s probably not literally or technically true, but it may be perceived that way.
I know a smattering of Italian and whether you use “in” or “a” (“in” or “to”) to refer to travel to an area depends on the area, by convention. In English we always say we go “to” this city or that country, but in Italian one goes “in Italia” but “a Roma,” for example. And there’s no rhyme nor reason to it.