how early do i need to arrive at an airport
Generally speaking, you must arrive at the airport one hour in advance of domestic flights and two hours in advance of international flights. What you should keep in mind, however, is that unless the international portion of your travel is nonstop from your origin city, you need only follow domestic flight guidelines.
Most airlines also require passengers be at the boarding gate approximately 30 minutes before departure. As airport processing times vary, Delta's website suggests arriving at the airport three hours before international travel, while Virgin America recommends allowing two hours.