Hurricane Betsy was a strong hurricane of the 1965 Atlantic hurricane season which caused a lot of damage in the Bahamas, Florida, and Louisiana. Betsy made its most strongest landfall near the mouth of the Mississippi River, causing major flooding of the waters of Lake Pontchartrain into New Orleans; at the time it was the costliest hurricane in the history of the United States, and, as the first hurricane to cause over a billion dollars in damages, earned the nickname "Billion-Dollar Betsy".