Handle for the month amounted to $17.2m (£14.2m/€16.5m), which was up from $13.7m in May of 2021 but 6.5% lower than $18.4m in April this year.
Revenue in May reached $2.0m, which was level with the same month last year and 42.9% higher than $1.4m in April 2022.
Breaking this down by individual operator performance, Caesars retained top spot with some $818,131 in revenue from $7.7m in players bets.
Gambet, which is operated by the DC Lottery and powered by Intralot, was second after paying out $4.3m in winnings from $5.0m in wagers, resulting in $724,451in revenue.
BetMGM, which operates in DC in partnership with Major League Baseball franchise the Washington Nationals, followed with $444,021 in revenue and a $4.0m handle.
Finally, Grand Central Restaurant, Bar and Sportsbook, which offers sports betting via an agreement with Elys Game Technology, placed fourth with $30,105 from $476,437 in wagers.