Anyone here owns a business that primarily sells online but also does fairs/markets? Question about sales tax when selling out of state!

Hi y'all. I'm starting my own home-based business in NJ and have a couple of questions. I'll mainly be doing apparel/accessories, and selling online via Etsy. BUT I also want to do weekend fairs/markets. So question: Since my business is registered in NJ and that's where I have my sales tax cert, what happens when I want to join a market in NY? Do I need to make an additional registration in the state of NY just to operate some weekends?