Some airports, like Denver's, aren't known for easy and cheap public transportation to the city center. But, in Airfarewatchdog.com's experience, these 10 U.S. airports make it easy to skip cab lines, traffic and high fares.

• Boston Logan: The Silver Line Rapid Transit Bus Service (SL1) will take you from Boston's Logan Airport straight to South Station, which is Boston's central transportation hub. There are also shuttle buses to/from the Blue Line subway train to each airport terminal.

• Washington Reagan National: The Washington D.C. Metrorail stops at the B and C terminals in this airport. From Terminal A, you can take a short bus ride to Terminal B or C to get on the train.

• San Francisco International: Hop on the Airtran at any terminal, for no cost, and get off at the Garage G/BART station stop. From there you can access the Bay Area Rapid Transit (San Francisco's train system).

• New York John F. Kennedy: You can get on the Airtrain for $5 at each terminal, and access the New York City Transit Authority subway or the Long Island Railroad. Get off at Airtrain's Howard Beach exit for transfer to the A subway train, or at Jamaica Station for transfer to the E, J and Z subway trains and the Long Island Railroad.

• Minneapolis-St.Paul International: The light rail trains stop at the Lindbergh terminal, then proceeds to key locations such as the Mall of America and downtown Minneapolis. From the Humphrey terminal, there is a shuttle bus to the Lindbergh terminal. However, the airport hopes to have light rail service to both terminals by Autumn 2007.

• Chicago O'Hare: The Airport Transit System (ATS) is a free train that connects all terminals to a Metra subway/train station. You can take the Metra to numerous locations in downtown Chicago.

• Philadelphia International: The SEPTA (Philadelphia's public transit system) connects directly to all terminals in this airport. You can hop on to the R1 high-speed rail line, which goes straight into downtown Philadelphia and other transportation hubs.

• Portland International: Portland's MAX light rail stops at the airport's central baggage claim. It's the last stop on the red line, which goes to downtown Portland and the City Center.

• Hartsfield-Jackson Atlanta International: MARTA (Atlanta's train system) stops at the airport's baggage claim area. This service will take you to downtown Atlanta within 20 minutes.

• Baltimore/Washington International: A free shuttle will take you from the terminals to the BWI Rail Station. From there, you can take the Maryland Rail Commuter Service (MARC) to either Penn Station in Baltimore or Union Station in Washington D.C.