In this article, we examine the relationship between the total number of types of gambling that are legal in a state and the gambling involvement of state residents. Of particular interest is whether more types of legal gambling are associated with higher rates of problem gambling. Telephone surveys of U.S. adults were conducted in 1999-2000 and 2011-2013. The same questions were used and the data sets were combined for most of the analyses. Gambling exposure was defined as the sum of the number of years that all types were legal. Results tabulated by state showed progressively higher rates of problem gambling, frequent gambling and any past year gambling as the number of legal types of gambling increased. Holding constant the number of legal types, problem gambling rates increased as exposure increased. States with longer exposure to legal lotteries or casinos tended to have higher rates of problem gambling. An analysis was also conducted in which the data sets from 1999 to 2000 and from 2011 to 2013 were compared. Among the states, there was a striking positive relationship between changes in the number of legal types of gambling between the two studies and changes in rates of frequent gambling between the two studies. For states that had fewer types of legal gambling in 2011 than in 1999, the rates of frequent gambling went down. For states that increased their types of legal gambling, rates of frequent gambling typically, but not always, went up. Possible explanations for these results were discussed.