May 1989 - Iowa Gov. Terry Branstad signs a bill legalizing low-stakes gambling on riverboats cruising the Mississippi or Missouri rivers.

September 1989 - By a 55 to 45 percent margin, Woodbury County voters approve riverboat gambling on the Missouri.

March 1990 - Iowa Racing and Gaming Commission awards state gambling license to the Woodbury County nonprofit gaming organization, Missouri River Historical Development (MRHD), and its California-based developer, Fried/Schagen. Seven months later, the commission revokes Fried/Schagen's portion of the license after it fails to secure financing.

November 1990 - The commission grants an excursion boat gambling license to MRHD and Bettendorf, Iowa-based Steamboat Development. After repeated delays, Steamboat voluntarily surrenders its portion of the license in March 1992.

July 1992 - The commission grants a license to MRHD and a local group of investors headed by Ted Carlson. The Sioux City Sue opens to gamblers in January 1993, and begins daily cruises the following spring.

May 1994 - Alton, Ill.-based Argosy Gaming acquires the Sue and replaces it with a larger excursion boat, called the Belle of Sioux City in December 1994.

September 2004 - Argosy unveils the Argosy IV, a floating casino three times larger than the Belle.

October 2005 - Wyomissing, Pa.-based Penn National Gaming, the nation's third largest gaming company, acquires Argosy Gaming. As part of the $1.4 billion deal, Penn National assumes Argosy's contract with MRHD.

July 2007 - Iowa eliminates requirement that casinos be located on water.

December - MHRD moves forward with plan to replace Argosy's Sioux City boat with a land-based casino.