While battling a tough economy, Michigan has lost out on more than USD 300 million in revenue from Native American casinos since the state's deal with seven tribes allowed them to halt payments, a Free Press analysis has found. The lost revenue could easily double by the time the tribal pact with the state expires in seven years. The tribes were obliged to pay the state a share of profits only as long as they held a slot machine monopoly in Michigan. That monopoly ended when the state opened gambling to other tribes in 1998.