The NLN website is a great start, but it is only one of the accreditation agencies. There is also the Commission for Collegiate Nursing Education (CCNE) that accredits BSN programs).
If you are looking for a BSN program in Illinois, I also recommend looking at the search tool for the American Association of Colleges of Nursing at American Association of Colleges of Nursing | Nursing Program Search. Select BSN and Illinios, and then press search. This search tool is good for all programs at the BSN level and above; it does not list associate degree or diploma programs.