How early should I arrive at the airport?

Whether flying domestic or international generally it is a good idea to arrive at the airport at least 2 hours before your flight. Arriving two hours before will allow for plenty of time to go through the line at the ticket counter, pass through security, and find your gate.

Factors: 
Airport size
Security Process
Domestic or International Flight
Gate Location
Concourse or Terminal Location
Your physical health

A word from the insider- "My biggest pet peeve is when a passenger arrives at the airport less than a half-hour before their flight. They generally do not have enough time to receive their boarding pass, go through security and make it to their gate before their flight is closed. Generally a flight will be boarded 25-45 minutes before the scheduled departure time. When a passenger arrives at the airport after their flight has started boarding, if they are listed as checked in, we must hold the flight until five to ten minutes before departure.
           When we hold a flight for that long, it makes it difficult for the ground crew to close up the plane, pull the jetbridge, and push the plane back without causing a delay. When the airline takes a delay, it inconveniences all the passengers on the flight. If the passenger is able to make it to the gate before the flight leaves, we must hold the flight until they are boarded, and settled in their seat.
            Many people will get angry after arriving late, and being told their flight is already closed. They may still see the plane at the gate, but what they don't understand is the door to the plane has already been closed. Once the door is closed, it will not be reopened until it reaches its destination."

What can I do if I am running late?
If you are running late and will not be able to arrive at least one hour before your flight, call the airline. They will be able to assist you and determine whether you will need to be rebooked for a later flight. Many times they will rebook you for a flight later in the day or the following day for little or no cost. Most airlines have policies in place in case of an emergency. If you call the airline within two hours of your scheduled departure time, they will be able to rebook you for a later flight. Never hesitate to call the airline if you have any questions. They have representatives available to assist you.