Old Bay Seasoning is a blend of herbs and spices originally created in Baltimore in 1939, with manufacturing passed to McCormick & Company in 1990. The seasoning is a mix of 18 herbs and spices, including celery salt (salt, celery seed), red pepper and black pepper, and paprika. Some of the other spices that may be used are bay leaves, mustard, cardamom, cloves, and ginger, as listed in the original product in the Baltimore Museum of Industry. It is regionally popular, especially in Maryland and Virginia, as well as in the other Mid-Atlantic states and parts of New England and the Gulf Coast. Old Bay is chiefly used to season crab and shrimp. It is used in various clam chowder and oyster stew recipes.

Source: Wikipedia