Yellowstone Tee Shirts Located in the heart of West Yellowstone, the aforementioned t-shirt company is not short on a slew of ooh-la-la shirts for a price. As the name implies, they are a subsidiary of Delaware North, which operates the yellowstone general stores for the National Park Service. The company has been in business since 1888 and is currently the largest T-shirt shop operation in the state. The company has an impressive selection of shirts and hats for men, women, and kids in their arsenal.