Many public libraries in the United States offer free or low-cost English classes or learning materials. For example, if you're in the Columbus, Ohio area, the Columbus Metropolitan Library offers an instructor-led, in-person English class, as well as a self-paced online English class (available through the library's website).
Additionally, public libraries also offer a variety of English language learning materials that can be borrowed for free with a library card. Materials can range from books, videos, online teaching databases (such as Mango Languages), and more.
Visit your nearest public library to see what classes or materials are offered near you!