Government and federal employees generally get paid twice a month according to the GS Pay Scale. But the frequency of payment may depend upon the branch or office of government the employees work. State Employees can also have varying pay schedules as individual states have their own laws. A number of states have weekly pay cycles, particularly for junior employees.
Generally speaking the frequency with which government employees receive their pay depends is related to how the local or state government manages its budget revenues. Because payroll is such a large expense, the government needs to ensure that appropriate revenues are coming in to meet the pay obligations or the debt obligations that fund payrolls for many states.
To find out specific pay cycle dates, check your states treasury site. Federal pay cycles are bi-monthly, unless noted otherwise.