A new law has come into effect in Russia, confining gambling to four regions far from the capital Moscow.
It bans gambling on the internet and at airports, supermarkets and other sites.
But critics say the move will leave more than 300,000 people without jobs and push the industry underground, amid a continuing economic crisis in Russia.
The law was passed by Russian lawmakers in 2006 and was the initiative of the then President Vladimir Putin, who is now serving as prime minister.
From 1 July, Russian gamblers are restricted to specific zones in the Kaliningrad region by the Baltic Sea, the Primorye region in the Far East, Altai in Siberia and an area in the south spanning the Rostov and Krasnodar regions.
Let them close. For that matter, get them out of Russia altogether
Galina Beleznikova, pensioner
The dedicated gambling zones require massive investment, and critics argue that they are far from ready.
"This is a dead unrealistic idea," Samuel Binder, deputy executive director at the Russian Association for Gaming Business Development, was quoted as saying by Reuters.
"It's preposterous to think these replacements could be up and running soon... Even those who have investments for gaming have realised they'd rather take their money elsewhere in the ex-Soviet Union or to Latin America," Mr Binder said.
Casinos and slot machines spread across Russia after the collapse of the USSR in 1991.
In Moscow alone, there were more than 500 legal casinos and gaming halls.
Police have been patrolling the streets in the capital to ensure the doors are firmly shut.
The spread of casinos has provoked distaste among many Russians, especially the older and poorer generation.
"Let them close. For that matter, get them out of Russia altogether," Galina Beleznikova, 65, told the Associated Press.
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