Hmm their website says they still do.
Q. Does the company still make chocolate in Hershey?
A. Yes! Our history in the town goes back more than 100 years, and we are committed to continue making the world's best chocolate products in Hershey, Pennsylvania. In fact, the company is creating one of the world's largest, most advanced chocolate facilities right here in Hershey. This project represents a significant investment and will ensure that we continue to make HERSHEY'S Milk Chocolate Bars, HERSHEY'S KISSES Milk Chocolates, HERSHEY'S Syrup and REESE'S Peanut Butter Cups as well as a wide range of other products in Hershey, Pennsylvania. We also make about a million miles of TWIZZLERS Candies each year at our Lancaster facility, a few miles from Hershey.
I believe they make them both in Mexico and USA.
Bruce