In addition to the United States, countries operating casinos
include France, England, Monaco (Monte Carlo of course) and
quite a few in the Caribbean islands.
The first recognized effort to apply mathematics to BlackJack
began in 1953 and culminated in 1956 with a published paper.
Roger Baldwin wrote a paper in the Journal of the American
Statistical Association titled "The Optimum Strategy
in BlackJack". These pioneers used calculators and probability
and statistics theory to substantially reduce the house advantage.
Although the title of their paper was 'optimum strategy',
it wasn't really the best strategy because they really needed
a computer to refine their system.