• According to the Hub Report in "USA Today," the main hubs for United Airlines are Chicago O'Hare, Denver, Washington Dulles, San Francisco and Los Angeles. The drop in the economy since 2001 has forced airlines to raise prices on or charge for checked luggage.
  
  

I.D. Requirements

• Passengers over the age of 18 are required to carry a photo I.D. for all U.S. domestic and international flights. For domestic flights, commonly used and accepted forms of I.D. include U.S. passport or passport card, a driver's license or other state issued I.D. card and a U.S. military card. For travel outside of the United States, including Costa Rica, Mexico and Canada, passengers are required to carry a passport and any necessary documentation and visas, which vary depending on the country, but could include a plane ticket out of the country and verification of funds to support yourself while traveling.
  
  

Carry-on Baggage

• To bring a bag onto a flight it must not be larger than 9 by 14 by 22 inches and no longer than 45 inches. The must fit into the overhead bin or under the seat and cannot be stored in the pouch behind the seat. If your carry-on luggage does not fit these requirements, you may be asked to check the bag. Items that are allowed on United Airlines flights in addition to a carry-on bag are food and drink for the flight, umbrellas, assistive devices such as canes or crutches, reading material, outerwear, infant carriers and child safety seats. All carry on liquids must be in a container no larger than 3.4 ounces and in a quart-sized clear plastic bag.
  
  

Checked Baggage

• As of January 14, 2010, U.S. domestic and Canadian flights checked bags must have a visible label with the name of the passenger who checked it in. During check in a United Airlines label is also printed with the passenger information on it. If you need to check a bag, United Airlines recommends arriving 90 minutes before the flight. Fees are charged for all checked luggage with exceptions given to military personnel either in active duty or on leave from active duty and for business class flights. Overweight bags carry extra fees. For international flights out of the U.S., bags must be checked at least 45 minutes before flight, and for flights into the U.S., bags must be checked 60 minutes before the flight.