Previous to the Supreme Court decision overturning the ban on sports betting, only permitted such forms of gaming. Now there are estimates that states will permit sports betting.

1.  Delaware, Montana, Nevada, and Oregon

2.  75%

Explanation:

Over the years in the United States, there was illegality of sport betting which means, the federal government of the United States placed ban on sport betting activities. However, there were exceptional states, that are considered to be the  pioneers or  the grandfather of sport betting, they include the following States : Delaware, Montana, Nevada, and Oregon.

Thus, recently, the Supreme Court of United States in May 2018, passed a ruling in which it is stated that the 1992 federal ban on sports betting in most states violated the rights of  a State.

Hence, with recent development on legality of sport betting ban in the United States, by the Supreme Court, it is estimated that about 75 percent of US states have either legalized sports wagering or have introduced its legislation.

Thereofore, Previous to the Supreme Court decision overturning the ban on sports betting, only  DELAWARE, MONTANA, NEVADA, and OREGON permitted such forms of gaming. Now there are estimates that 75 PERCENT states will permit sports betting.

the answer is migration

yes i think there would be volunteers