Travel smarter not harder by knowing how to navigate the ins and outs of the three busiest airports in the U.S.

Saving time at Hartsfield-Jackson Atlanta International Airport (ATL)

Not only is Atlanta’s Hartsfield-Jackson International Airport one of the most active in the U.S., it is the busiest airport in the world by passenger volume. ATL has two main terminals: the international terminal on the east side and the domestic terminal on the west side.

The domestic terminal features a central atrium with two offshoots: the south terminal servicing Delta Airlines and the north terminal servicing all other airlines, with the Plane Train connecting all domestic concourses.

Perhaps one of the airport’s best kept secrets, the international terminal can provide passengers access to the airport without the forever-long security lines found in the domestic terminal. Great for travelers flying carry-on only, you’ll need to check-in online and print your boarding pass ahead of time unless flying Delta – which has a desk in the international terminal – to take advantage of this airport hack.

Travelers departing from Atlanta have many parking options offered by off-site airport parking providers that often offer added services and amenities. Off-site airport parking can be found for as cheap as $11.50 per day, while daily airport rates can reach as high as $36 per day.

Additionally, many off-site parking providers offer direct access to the international terminal, cutting down on time spent at security.

Saving time at Los Angeles International Airport (LAX)

As a gateway to international travel, particularly to Asia and the Pacific, LAX records nearly 1,400 weekly flights to more than 40 countries and daily nonstop flights to approximately 100 domestic destinations. Spread over nine passenger terminals, travelers with connecting flights must often exit and re-clear security to access its other terminals. Select terminals are linked via an airside connection that provides direct access to the other terminals.

A minimum of a two-hour layover for domestic flights and three hours for international is required to avoid missing a connecting flight.

Avoid getting lost and check your gate number to get an idea of where to catch your connecting flight. The first number refers to the terminal and the second to the gate with even-numbered gates on the left of the terminal and odd numbers to the right.

Traffic around LAX will easily add an additional 30 minutes or more to your trip no matter what the GPS says, so plan accordingly. Long-term parking is located within the central loop, and each structure is numbered to correspond with the nearest terminal. Off-site parking also is an option for those looking to save some time.

Saving time at O’Hare International Airport (ORD)

The largest airport in the U.S. by total flights, Chicago’s O’Hare has four main terminals: Terminal 1 servicing United Airlines; Terminal 2 servicing a variety of airlines; Terminal 3 servicing American Airlines; and Terminal 5, exclusively servicing international flights.

So, where’s Terminal 4? The mystery terminal no longer exists, having been replaced by Terminal 5 in 1993.

The three domestic terminals are connected, but travelers must board the Airport Transit System (ATS) to access the international terminal from domestic and vice versa.

Travelers also have the option of taking the Terminal Transfer Bus (TTB) from Terminal 3 to 5 to avoid having to re-clear security upon entry. While the TTB allows you to bypass security, it is only operational from 10 a.m. to 8:30 p.m. Those who will be changing carriers or who need to collect and recheck their luggage, cannot access this service. The TTB picks up at Gates G17, K20 and L24 in the international terminal.

Parking rates at O’Hare can reach as high as $40 per day for departing travelers, with off-site parking options starting as low as $10.99 for travelers departing from Chicago.