St Marys Depot A St. Marys Railroad diesel locomotive sits beside the depot/shop building in St. Marys. Behind it is the former Gilman paper manufacturing plant. Located on the coast in Georgia's southeast corner, St. Marys is a growing town of 16,000 people.   Georgia's Railroad History & Heritage. Copyright, Steve Storey. Railroad History | The Depot List | Locomotives On Display | Odds & Ends | Sources & References | Home