Is California the only state in the U.S. where a company can not legally claim ownership of your side projects as long as they do not relate to company business

Is California the only state in the U.S. where a company can not legally claim ownership of your side projects as long as they do not relate to company business? I will eventually move out of the Bay Area, and this is my biggest concern for a new job. Financially, I don't have enough saved up to just quit and work on a startup for a year, but I also don't want my full time employer to own a side project that ends up being successful. What is the best way to handle this? How amenable are companies outside of California to negotiating away the invention assignment clause?