Mobile is the third most populous city in the state of Alabama and is located in the southwestern corner of the state. Mobile's geographical location on the Gulf of Mexico provides a mild subtropical climate. Located at the junction of the Mobile River and Mobile Bay on the northern Gulf of Mexico, the city is the only seaport in Alabama. The Port of Mobile is the 10th largest port in the United States. As one of the Gulf Coast's cultural centers, Mobile houses several art museums, a symphony orchestra, a professional opera, a professional ballet company, and a large concentration of historic architecture. Mobile is known for having the oldest organized Carnival/Mardi Gras celebrations in the United States, as well as the oldest Carnival mystic society, dating to 1830.