This wouldn't just be the US. In Spanish-speaking countries (though technically America as in North/Central/South America), "profesor" can refer to either a high school educator or a university professor: https://www.spanishdict.com/translate/profesor
I would be glad to hear more from native Spanish speakers or other foreign language speakers who use similar terms (e.g. French speakers, who also use the word "professeur" with a similar usage).
However, there are nuances. The term "catedrático" is used for senior profesors/profesores at a university: https://spanish.stackexchange.com/questions/21816/what-is-th...
I would be glad to hear more from native Spanish speakers or other foreign language speakers who use similar terms (e.g. French speakers, who also use the word "professeur" with a similar usage).