There is no base salary in any state.
In order to be classified as exempt (note that NOT all salaried employees are exempt) there is a federal floor of $455 weekly; meaning that if your salary is less than $455 weekly, you are automatically non-exempt. It does not mean that no salaried employee can receive less than $455 per week - it means that if they do, they are non-exempt (and eligible for overtime). There are a very few states where that amount is higher; I do not recall that Maine is one of those states but Patty will know when she comes by.
In all cases, how many hours any employee (exempt, non-exempt, hourly or salaried) works per week is up to the employer.