The 2004-05 NHL lockout was a labor dispute in the National Hockey League that caused the cancellation of the league's entire 2004-05 season. The dispute had a significant impact on poker's popularity in Canada and those parts of the United States where ice hockey is a popular sport.
The cause of this hockey-related matter's impact on poker lies in hockey's dominant presence in the sports programming of Canadian as well as some U.S. networks. Especially in Canada sports networks filled a significant portion of their open programing slots with no-limit Texas hold 'em, greatly increasing the game's exposure. Although the surge in this variant's popularity can be traced back to 2003, at the start of the hockey lockout many sports fans were all but unfamiliar with community card variants of poker such as Texas hold 'em. By the end of the lockout there had been a massive increase especially in the number of Canadians and also Americans who had become accustomed to Texas hold 'em.
While the lockout was not the proximate cause of the surge in the popularity of Texas hold 'em, it certainly did accelerate the surge to a signifcant degree.