the Riverchase Galleria, one of the largest shopping centers in the southeast; Guntersville Lake, voted the best lake in Alabama by Southern Living Magazine readers; and the Alabama Museum of Natural History, the oldest museum in the state. Mobile is known for having the oldest organized Mardi Gras celebration in the United States, beginning in 1703. It was also host to the first formally organized Mardi Gras parade in the United States in 1830, a tradition that continues to this day. Mardi Gras is an official state holiday in Mobile and Baldwin counties. In 2018, Mobile's Mardi Gras parade was the state's top event, producing the most tourists with an attendance of 892,811. The top attraction was the U.S. Space & Rocket Center in Huntsville with an attendance of 849,981, followed by the Birmingham Zoo with 543,090. Of the parks and natural destinations, Alabama's Gulf Coast topped the list with 6,700,000 visitors. Alabama has historically been a popular region for film shoots due to its diverse landscapes and contrast of environments. Movies filmed in Alabama include: Close Encounters of the Third Kind, Get Out, 42, Selma, Big Fish, The Final Destination, Due Date, Need For Speed and many more. Healthcare UAB Hospital, USA Health University Hospital, Huntsville Hospital, and Children's Hospital of Alabama are the only LevelI trauma centers in Alabama. UAB is the largest state government employer in Alabama, with a workforce of about 18,000. A 2017 study found that Alabama had the least competitive health insurance market in the country, with Blue Cross and Blue Shield of Alabama having a market share of 84% followed by UnitedHealth Group at 7%. Banking Regions Financial Corporation is the largest bank headquartered in or operating in Alabama. PNC Financial Services and Wells Fargo also have a major presence in Alabama. Wells Fargo has a regional headquarters, an operations center campus, and a $400million data center in Birmingham. Many smaller banks are also headquartered in the Birmingham area, including ServisFirst and New South Federal Savings Bank. Birmingham also serves as the headquarters for several large investment management companies, including Harbert Management Corporation. Electronics and communications Telecommunications provider AT&T, formerly BellSouth, has a major presence in Alabama with several large offices in Birmingham. Many technology companies are headquartered in Huntsville, such as ADTRAN, a network access company; Intergraph, a computer graphics company; and Avocent, an IT infrastructure company. Construction Brasfield & Gorrie, BE&K,