DETROIT -

Revenue from Detroit's three casinos fell by 4.7 percent this past year, making it the highest decline since the three casinos opened up in 2001.

MGM Grand Detroit, MotorCity Casino and Greektown Casino combined for a total revenue of about $1.35 billion, down from $1.42 billion in 2012.

That could cost the city about $10 million a year.

The city gets about 14 percent of its total revenue from casino taxes.

View: 2012 Detroit casino revenue
View: 2013 Detroit casino revenue