The drink was first sold in Waco (McLennan County), Texas, in 1885. It was introduced nationally in the United States at the 1904 Louisiana Purchase Exposition. The exact date of Dr Pepper's conception is unknown, but the U.S. Patent Office recognizes December 1, 1885 as the first time Dr Pepper was served.
It was formulated by German pharmacist Charles Alderton in Morrison's Old Corner Drug Store in Waco, Texas. To test his new drink, he first offered it to store owner Morrison, who also found it to his liking. After repeated sample testing by the two, Alderton was ready to offer his new drink to some of the fountain customers. They liked it as well. Other patrons at Morrison's soda fountain soon learned of Alderton's new drink and began ordering a "Waco." Alderton gave the formula to Wade Morrison, the owner of the drug store. A popular belief is that the drink was named after Morrison's former employer in Texas, but this has been disputed by the Dr Pepper company itself. They state that before moving to Texas, Morrison lived in Wythe County, Virginia near a Dr Charles T. Pepper, and may have been close to Pepper's daughter at the time. The name is also reinforced by being an obvious play on "pep", i.e. providing quick energy to its consumer.
Unlike Coca-Cola and Pepsi, Dr Pepper is not marketed as a cola. Dr Pepper's flavor is allegedly derived from a mixture of soda fountain flavors popular when the drink was first devised. A partial list of these flavors can be seen at the bottling plant in Dublin, Texas, although the formula itself (with its twenty-three ingredients) is a closely guarded secret. Contrary to a popular urban legend, Dr Pepper does not and never has contained prune juice.  In Texas, Dr Pepper is extremely competitive in the soft drink market, regularly outselling Pepsi and Coca-Cola. 
The Dr Pepper Museum, located in Waco, TexasThere is also a Dr Pepper Museum in downtown Waco, Texas. It is located in the Artesian Manufacturing and Bottling Company building in downtown Waco, and opened to the public in 1991. The Artesian Manufacturing and Bottling Company building was the first building to be built specifically to bottle Dr Pepper. The building was completed in 1906 and Dr Pepper was bottled there until the 1960s. The museum has three floors of exhibits, a working old-fashioned soda fountain, and a gift store full of Dr Pepper memorabilia. (As the picture shows, the building has differing color bricks, since it was heavily damaged by the Waco Tornado.)
It is notable that Dr Pepper almost became a Coca-Cola brand in the mid-to-late 1980's. Dr Pepper became insolvent in the early 1980's, prompting an investment group to take the company private. Several years later, Coca-Cola attempted to aquire Dr Pepper, but was blocked from doing so by the FTC. Around the same time period, Seven Up was aquired from Phillip Morris by the same investment company that bailed out Dr Pepper. Upon the failure of the Coca-Cola merger, Dr Pepper and Seven Up merged (creating Dr Pepper/Seven Up, Inc., or DPSU), giving up international branding rights in the process. After the DPSU merger, Coca-Cola obtained most non-U.S. rights to the Dr Pepper name (with PepsiCo taking the Seven Up rights).
Hope this interesting information helps all of those passengers who will experience Dr Pepper for the first time.
JIM, THANKS FOR THE CONFIRMATION...YOU SEE, MY WIFE MAKES ME CALL THE CRUISE LINES BEFORE WE GO ON A CRUISE TO CONFIRM IF THEY DO, OR DO NOT HAVE DR. PEPPER ON BOARD.. WHEN I CALLED NCL, THEY SAID THEY USUALLY DON'T HAVE DR. PEPPER, BUT BECAUSE BEING IN TEXAS AND BECAUSE OF THE GREAT DEMAND, THEY HAD TO START CARRYING IT FOR THEIR CUSTOMERS... ISN'T THAT SOMETHING???
Originally posted by Jim C.:
Ron I can confirm what Vicster claims.. Must be their idea of a "texarribean cruise" to have a Texas staple like Dr P. But they did have it for our October cruise.
Maybe I did see some Dr. Pepper aboard the Dream on my December 9-16 cruise, but I thought most brought it aboard themselves, as they were all in cans. I do know I couldn't buy Dr. Pepper with my adult soda card as a fountain drink.
I live 30 miles away from Dublin, Texas where they still make Dr. Pepper with the original formula, using sugar cane in the syrup vs corn syrup. So, I do love to drink Dr. Pepper, but not what they bottle in big cities like Houston.
You really can taste the difference between sugar cane and corn syrup.
Never-the-less, NCL usually only carries Coka Cola products aboard their ships; Coke, Sprite, and Diet Coke. It's possible that the Dream sailing from Houston may be the only exception.