Peninsula was acquired in November 2012 by Boyd Gaming. In 2006, Peninsula opened a second Diamond Jo Casino in Northwood, Iowa, 200 miles (320 km) from Dubuque. Peninsula Gaming continues to operate the casino. In July 1999, Dubuque-based Peninsula Gaming purchased the casino operation, and spent $1 million updating the riverboat. After a year and a half, in October 1995, that boat was replaced with a larger, 1,500-passenger riverboat.

The 'first' Diamond Jo Casino began operations on May 18, 1994. The name honors businessman Joseph 'Diamond Jo' Reynolds, who owned a Dubuque shipping company, among other enterprises. The organization selected the Greater Dubuque Riverboat Entertainment Company L.C., and its boat, which was later named the Diamond Jo, following a local naming contest. Soon after, the DRA began to search for a new riverboat to operate under the gaming license already in place. This boat's operation was short-lived, however, and relocated to Missouri in 1993, following a change in ownership. On April 1, 1991, the Dubuque Racing Association (DRA) and local businessman Robert Kehl opened Iowa's first riverboat casino in Dubuque's Ice Harbor, the Casino Belle.

The operation had 3 restaurants: the Diamond Deli, HighSteaks Restaurant, and Jo's Café. It has 777 slot, keno, and video poker games, and 17 table games, including: Big Raise Hold 'em, Blackjack, Craps, Four card poker, Let It Ride, Roulette, Texas Hold 'em, and Three card poker.

The casino, along with the nearby National Mississippi River Museum & Aquarium and other attractions, have helped to create a large and growing tourism market in Dubuque.Īs a riverboat operation the Diamond Jo was the smaller of Dubuque's two casinos, with 19,600 square feet (1,820 m 2) of gaming space. The Diamond Jo Casino is located at 301 Bell Street, in the rapidly developing Port of Dubuque. The boat was a dockside that did not cruise, the casino became land-based when its new facility opened December 11, 2008. Beginning operations on May 18, 1994, the Diamond Jo was a 3-level, 305-foot (93 m), 1,500-passenger vessel in Dubuque's Ice Harbor. It is a member of the Iowa Gaming Association, and its license is held by the Dubuque Racing Association, which operates Q Casino. The casino is owned and operated by Las Vegas-based Boyd Gaming, which also owns the Diamond Jo Casino - Worth in Northwood, Iowa. The Diamond Jo Casino is a gambling casino and entertainment complex located in the Port of Dubuque, in Dubuque, Iowa.

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