Chicago O’Hare Airport

O’Hare is an airport of superlatives, but in its own way. It is not the number of long-haul airlines that makes it special, but the sheer density: two of the largest airlines in the world, United and American, each run one of their most important hubs here. In 2025, that added up to a good 857,000 takeoffs and landings – on average more than 2,300 a day. Add a runway system that has been completely rebuilt over the past two decades. For spotters, that means: lots of traffic, lots of types, but also a sprawling site that demands planning.

From aircraft plant to world airport

The story of O’Hare does not begin with passengers but with arms production. During the Second World War, a large Douglas plant arose on Chicago’s then still rural northwest edge. Four-engine C-54 Skymaster transport aircraft rolled off the line there and took off from the factory airfield right next door. When Douglas left after the war, the city took over the site. It was now called Orchard Field – after the small settlement of Orchard Place that had previously been there – and received the code ORD, which is still on every baggage tag today.

In 1949, Chicago renamed the airport after Edward “Butch” O’Hare, a naval aviator from the city who had become known in the Second World War and fell in the Pacific in 1943. The old code was kept – which is why people still fly to “ORD” even though the name begins with O. Scheduled passenger service started in 1955, at first still in the shadow of the inner-city airport Midway.

The leap to the top of the world

With the jet age, Midway became too small, and O’Hare took over. On January 1, 1962, the new Terminals 2 and 3 opened, designed by the Chicago firm C. F. Murphy and Associates. By 1963, O’Hare was the busiest airport in the world by passengers – and stayed that way until 1998, when Atlanta Airport overtook it. In those decades, Chicago was the synonym for connecting traffic in the heart of the USA.

Its darkest chapter belongs to the history as well. On May 25, 1979, a McDonnell Douglas DC-10 of American Airlines, as Flight 191, lost its left engine shortly after takeoff and crashed. 273 people died, including two on the ground – to this day the deadliest aviation accident on US soil.

Jahn’s terminal and the light show

In the mid-1980s, United got a new home. Between 1985 and 1987, today’s Terminal 1 was built to plans by the architect Helmut Jahn, with its bright, vaulted steel-and-glass halls. Famous is the underground walkway between Concourses B and C: moving walkways and a colorful neon light installation on the ceiling make it one of the best-known airport tunnels anywhere. In 1993 followed the International Terminal, which is now called Terminal 5 and consolidates all customs and immigration facilities.

The runway system: from pick-up sticks to parallel runways

Anyone who knows old aerial photos of O’Hare remembers a tangle of runways in three directions that crossed repeatedly. That made operations complicated in wind and bad weather and cost capacity. So in 2005, the US aviation authority FAA approved the O’Hare Modernization Program. Its goal: a system of mostly parallel east-west runways on which several approaches can run independently of each other.

The program stretched over about 16 years. In October 2013, runway 10C/28C entered service, the first runway in Chicago designed for the largest airliners. In 2015, 10R/28L was added, and at the same time the crosswind runway 14L/32R closed. In 2019 came the decommissioning of the last major crosswind runway 14R/32L, and in 2020 9C/27C opened. With the extension of 9R/27L, the program ended in 2021. The old runway 18/36 had already been converted into a taxiway in 2001.

How to read a runway’s orientation from the digits and what L, C and R mean is explained in the article on runway designations. At O’Hare the suffixes are especially important: with three parallel runways per group, “Center” is needed besides left and right.

West or east operations

For your spotting day, one question matters most: are operations currently toward the west or the east? Since six of the eight runways run east-west, the runway direction in use at O’Hare is mostly either “West Flow” with takeoffs and landings toward the west or “East Flow” toward the east. In west flow, approaches come in over the residential areas east of the airport; in east flow, from the west. The diagonal runways are added mainly with suitable wind. The article Understanding the runway direction in use at airports provides the basics.

A special spectacle is the parallel approaches. In good conditions, aircraft land side by side on two or three runways at the same time. If the sun is right, you get several aircraft in one picture – a subject hardly possible at European airports. How instrument approaches work and why they are possible in parallel at all is explained in the article on the ILS approach.

Two home airlines, two worlds

O’Hare is one of the few big hubs where two network airlines of similar size operate side by side. According to US transportation statistics, United Airlines most recently accounted for just under half of the passengers and American Airlines for about a third. Both airlines build their schedules in waves in which arrivals and departures bunch up. How to use these hub waves for your spotting day is covered in the article on banking at hubs.

United is mainly in Terminal 1 and parts of Terminal 2. The airline belongs to the Star Alliance and has its headquarters in Chicago – O’Hare is therefore its home airport. Its partners such as Lufthansa and All Nippon Airways also use Terminal 1. American, by contrast, has Terminal 3, together with partners from oneworld such as British Airways, Iberia, Japan Airlines and Aer Lingus.

The assignment of airlines to terminals keeps changing because of the ongoing rebuild. As of fall 2026, the table serves as a rough guide – check the airport’s current information before your visit.

What you realistically see

O’Hare is a paradise for anyone who likes to see lots of aircraft in a short time. Most are narrowbody jets and regional jets in domestic traffic. At United you meet the Boeing 737 MAX 9, the 737-900ER and the A320 family; at American, among others, the A321neo and the 737-800.

A large share of flights operate under the regional brands United Express and American Eagle. Behind them are regional airlines such as SkyWest, Republic Airways and Envoy Air, which mainly operate the Embraer E175 and Bombardier jets such as the CRJ700 and CRJ900. How to tell the many similar regional jets apart is explained in the article Identifying regional jets.

On long-haul, the two home airlines mainly use Boeing 787s and 777s, such as the Boeing 787-9 and the 777-200ER; depending on the rotation, a 777-300ER is in the mix too. Foreign carriers from Europe, Asia and the Middle East come on top. The busiest international route by passengers goes to London Heathrow.

Cargo at O’Hare

Besides passengers, O’Hare is one of the most important cargo airports in the USA. In 2025, about 2.2 million tonnes of cargo were handled. Two areas share the cargo traffic: the South Cargo Area in the south of the grounds and the Northeast Cargo Area, which arose on the former Douglas plant site – the place where the airport’s history began.

Cargo airlines such as Atlas Air and Polar Air Cargo are represented, as are the cargo divisions of large international airlines, including Lufthansa Cargo. Here you have good chances of freighters like the Boeing 777F or the 747-400F. How to tell freighter versions of passenger aircraft apart is in the article Identifying freighters.

The big construction site: O’Hare 21

After the runway system, the terminals are next. In 2018, the city approved the O’Hare 21 program, which comprises about 8.5 billion US dollars. The main building blocks:

• O’Hare Global Terminal: It replaces the old Terminal 2 in the center of the terminal ring and creates modern gates for international and connecting traffic.
• New satellites: Detached concourses create additional gates. Construction of Satellite D with 19 gates began in August 2025.
• Terminal 5: The program provides additional gates here, including for the Airbus A380.

In total, the number of gates is to rise from about 185 to about 235. The overall program is scheduled through 2030 – with projects of this size, schedules tend to slip. For you as a spotter, that means: access roads, sight lines and airline positions in the terminal area will keep changing over the next few years.

Spotting at O’Hare

There is no official visitor park at O’Hare like at Frankfurt Airport or Munich. Spotters therefore photograph from public roads, parking lots and green spaces around the grounds. Which location fits depends almost entirely on whether west or east flow is currently in effect. You will find specific locations, directions and light for individual sides of the airport in the article Plane spotting at Chicago O’Hare.

The east-west logic

Because almost all runways run east-west, the classic approach shots arise at the two ends of the runway system. In west flow, aircraft come in over the eastern suburbs; in east flow, from the west. The sun moves over the day from east through south to west – so on the north side of the airport you more often have light at your back than on the south side. Always plan two options and decide only in the morning.

Winter in Chicago

Chicago is known for harsh winters with snow, ice and an icy wind off Lake Michigan. For spotters, that has two sides: the cold demands stamina, but it creates subjects you do not get in summer – deicing with steam clouds, snow fountains at takeoff and clear, high-contrast winter days. Tips on clothing and camera are in the article Plane spotting in winter, with background in the article on deicing aircraft.

Getting there by Blue Line and ATS

O’Hare is one of the few big US airports reachable by rail around the clock. The CTA Blue Line has its terminus directly beneath the terminal area and runs to downtown without changing trains. Within the airport, the Airport Transit System connects the terminal core with Terminal 5 and the Multi-Modal Facility, where rental cars, buses and a station of the Metra commuter rail are located. The ATS was modernized and has run around the clock again since April 2022.

For a spotting day without a rental car, though, that only goes so far: the locations at the runway ends are far from the terminal. If you want to cover several sides, a car or ride service is more flexible. A night at the Hilton Chicago O’Hare, the only hotel directly on the grounds, saves the commute in the morning.

O’Hare compared

Chicago has a second major airport in Midway, which handles mainly domestic and low-cost traffic. Nationwide, O’Hare stands in line with the other big hubs: Atlanta Airport is the Delta stronghold, Dallas/Fort Worth Airport American’s largest hub. Newark Airport, like O’Hare, is an important United hub, while New York JFK Airport is the international gateway on the East Coast. In the west, Los Angeles Airport completes the picture.

Across the Atlantic, O’Hare is closely tied to Europe: the connection to London Heathrow Airport is the most important international route, and with Lufthansa, a German airline is at home in Terminal 1, too.

Conclusion

O’Hare is an airport for everyone who loves movement. Two big home airlines, hundreds of regional jets, heavy cargo traffic and a runway system with parallel east-west runways ensure that the sky over Chicago’s northwest is rarely quiet. There is no comfortable visitor park, and the site is sprawling – but if you settle runway direction, light and hub waves beforehand, you will experience one of the most intense spotting days the USA has to offer.

Then there is the history: from the Douglas plant through the decades as the busiest airport in the world to the big rebuild that reorganized the runway system and is now reaching the terminals.