By the 1840s, farming had transformed the western frontier into America’s breadbasket, and moving grain to national and worldwide markets required vast numbers of specialized ships. In the age of sail, purpose-built canal schooners filled Great Lakes harbors and dominated the grain trade. The Welland Canal’s 150-foot by 26-foot locks limited the size of ships that could pass between Lakes Erie and Ontario, so canal schooners were built just a few feet shorter and narrower to maximize cargo on every trip. Some had hinged bowsprits and stern davits that folded inboard to allow the greatest possible hull length within the locks. Even with these efficiencies, many ships were needed: in 1862, Buffalo alone received over 58 million bushels of Midwest grain, while a typical canal schooner carried just 16,000 bushels per trip. By 1871, two thousand schooners sailed the Great Lakes, most carrying grain eastward and coal westward. Dozens later sank in what is now Thunder Bay National Marine Sanctuary, where Lake Huron’s cold, fresh water has preserved them as underwater museums of the Great Lakes’ maritime history.