Top 10 Gambling Countries by Revenue and ParticipationAnalysts usually rank the top 10 gambling countries using three factors: total revenue, how many residents bet regularly, and how fast the local market is growing. If someone asks what countries have casinos in the greatest numbers, the answer is the United States, and it isn’t close. California, New Jersey, Pennsylvania, and Michigan lead in both casino density and online betting adoption, while several states still ban commercial casinos outright. The UK and Europe’s Other Major Betting MarketsThe United Kingdom remains the most established gambling country in Europe. Final ThoughtsThe biggest gambling countries aren’t the same list depending on the metric you’re measuring: money, participation, or infrastructure.