As of January 2018, there are 37 states with slots in gas stations. These are designated for gasoline that is not ethanol.
The amount of gasoline that can be pumped without the use of an ethanol blend varies by state, but is typically around 10% or less. Some states, such as California and New York, have bans on the use of any gasoline that does not contain at least 10% ethanol.
The benefits of slots are twofold. First, they help to reduce the amount of petroleum-based fuel that is used in vehicles. This is because ethanol-free gasoline is cheaper than traditional gasoline, and consumers are more likely to choose it if it is available at their local station.
Second, slots help to reduce the amount of air pollution produced by vehicles. This is because ethanol-free gasoline has a lower emissions profile than traditional gasoline.