Final answer:
The Middle States Commission on Higher Education, established in 1919, is one of the oldest accrediting bodies, providing accreditation to colleges and universities for over a century.
Step-by-step explanation:
The accrediting body that has been established the longest is likely the Middle States Commission on Higher Education (MSCHE). Established in 1919, MSCHE has been in existence for over a century and is a voluntary, non-profit association that provides accreditation to colleges and universities in the Mid-Atlantic region of the United States. Accreditation is essential in ensuring educational institutions meet certain standards of quality and rigor. While MSCHE is one of the oldest, there are other regional and national accrediting bodies each with its own history and set of standards.