Slots generated more than $873.6 million this July, a 60% increase from the same month in the previous year. One of the main reasons behind this record haul was slot machines. 27 that we wrote about casinos in Nevada raking in a total of $1.36 billion from patrons in July, the highest single-month revenue from gaming for the state since gambling was legalized back in 1931. Slot machines are considered to be among the most lucrative games on the casino floor for both players and the house.