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Carnival celebrations, usually referred to as Mardi Gras (Fat Tuesday in French), were first celebrated in the Gulf Coast area, but now occur in many states. Customs originated in the onetime French colonial capitals of Mobile (now in Alabama), New Orleans (Louisiana) and Biloxi (Mississippi), all of which have celebrated for many years with street parades and masked balls. Other major American cities with celebrations include Washington, DC; St. Louis, Missouri; San Francisco; San Diego; Galveston, Texas; and Miami, Pensacola, Tampa, and Orlando in Florida.

What originated in the onetime French colonial capitals?
Answer: Customs
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The Soviets also helped Germany to avoid British naval blockades by providing a submarine base, Basis Nord, in the northern Soviet Union near Murmansk. This also provided a refueling and maintenance location, and a takeoff point for raids and attacks on shipping. In addition, the Soviets provided Germany with access to the Northern Sea Route for both cargo ships and raiders (though only the commerce raider Komet used the route before the German invasion), which forced Britain to protect sea lanes in both the Atlantic and the Pacific.

What did the Germans use to avoid British blockades?
Answer: a submarine base
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Greater London's population declined steadily in the decades after the Second World War, from an estimated peak of 8.6 million in 1939 to around 6.8 million in the 1980s. The principal ports for London moved downstream to Felixstowe and Tilbury, with the London Docklands area becoming a focus for regeneration, including the Canary Wharf development. This was borne out of London's ever-increasing role as a major international financial centre during the 1980s. The Thames Barrier was completed in the 1980s to protect London against tidal surges from the North Sea.

What event preceded a substantial decrease in the average population in London?
Answer:
the Second World War