New York to Chicago

Between New York and Chicago, 5.7 million passengers flew nonstop in 2025, on 47 thousand flights of about 730 miles and 1.8 hours in the air. The average passenger accounted for about 125 kg of CO2 from the fuel burned, from 95 kg on Spirit Airlines to 215 kg on Envoy Air.

On New York to Chicago the size of the plane decides most of the answer. Spirit, at 95 kg, and Southwest, at 106 kg, sit at the bottom. Envoy, Republic and Endeavor, flying jets of 76 seats or fewer, are at 215, 188 and 195 kg, roughly twice as much, and together they carried 10% of the passengers.

United has changed the route most. It carried 33% of the passengers in 2019 and carries 46% now, and its figure fell from 131 kg to 112 kg. Because it carries nearly half the passengers, that improvement accounts for much of the route's fall from 139 kg to 125 kg, a 10% cut.

125 kgCO2 per passenger, average
730 milesabout 1.8 hours in the air
5.7 millionpassengers in 2025
85%of seats filled

CO2 per passenger, airline by airline

Kilograms of CO2 per passenger, one way, 2025. Fuel burned only. Less is better.

New York to Chicago by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
United Airlines	46%	17.5	Boeing 737-800, Boeing 737-900ER	171	87%	112
American Airlines	19%	8.3	Boeing 737-800, Airbus A319	156	84%	129
Southwest Airlines	11%	4.6	Boeing 737 MAX 8, Boeing 737-800	166	82%	106
Delta Air Lines	8%	4.2	Airbus A220-300	122	85%	123
Envoy Air	4%	4.4	Embraer 175	67	83%	215
Spirit Airlines	4%	1.3	Airbus A320-200, Airbus A320neo	186	85%	95
Republic Airways	3%	3.1	Embraer 175	76	85%	188
JetBlue	2%	1.0	Airbus A220-300, Airbus A320-200	142	82%	149
Endeavor Air	2%	1.7		76	86%	195

What explains the differences

It's number 4 of the 100 busiest city pairs by passengers, and number 71 for the lowest CO2 per mile flown (0.17 kg per passenger-mile, number 1 being the lowest). A typical route of 730 miles in this set comes out at about 118 kg, so this one is 5.4% above it.

The flights use more than one pair of airports: ORD to LGA (49%), ORD to EWR (29%), MDW to LGA (11%). The figures here cover all of them.

The airlines on this route differ by 126% per passenger. Spirit Airlines burned 1,550 gallons per flight and 159 passengers on each, and Envoy Air 1,238 gallons and 56 passengers. The gap comes from how many passengers share each flight, not from fuel burned per flight. Spirit Airlines flew 85% full here against 83% for Envoy Air, flying mostly Airbus A320-200 against Embraer 175.

For comparison, the EPA default factor for a flight of this length (0.129 kg per passenger-mile) would give 94 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 32% higher.

2019 compared with 2025

In 2019 the route carried 6.1 million passengers on 56 thousand flights. In 2025 it carried 5.7 million, down 7%, on 47 thousand flights, down 16%. The average flight had 131 seats then and 143 now, and 84% of them were filled against 85%.

CO2 per passenger was 139 kg in 2019 and 125 kg in 2025, down 10.3%. Fuel burned per flight was down 0.8% (1,564 gallons to 1,553) and passengers per flight were up 10.7% (110 to 121). The distance flown was about the same (730 miles then, 730 now).

United Airlines led in both years, with 33% of passengers in 2019 and 46% in 2025. American Airlines lost the most, 26% to 19%. SkyWest Airlines and Air Wisconsin Airlines no longer reach 1% of passengers, having had 7% in 2019.

Airline by airline, Delta Air Lines went from 175 kg to 123 kg per passenger (110 seats per flight to 122, main aircraft Airbus A320-200 then and Airbus A220-300 now); Endeavor Air went from 176 kg to 195 kg per passenger (76 seats per flight to 76, main aircraft unlisted aircraft in both years).

New York to Chicago, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	6,104	5,707
Flights (thousands)	55.6	47.0
Seats filled	84%	85%
Gallons of fuel per flight	1,564	1,553
kg CO2 per passenger	139	125

Kilograms of CO2 per passenger on the airlines that flew the route in both years. 2019 figures use that year's filings and estimated aircraft fuel rates, with type-average replacements for missing or outlying filings as described in the methodology. Less is better.

New York to Chicago and back: time in the air

Flights from New York to Chicago spent 117 minutes in the air on average in 2025, against 98 minutes from Chicago to New York: 18 minutes longer, 19% more. That's the westbound direction, into the prevailing west-to-east winds, which at flight levels often blow at well over 50 miles an hour.

At this route's average burn of about 867 gallons per flight hour, those extra minutes cost about 266 gallons per flight, which is about 2.2 gallons or 21 kg of CO2 for each passenger on the slower direction. The route figure above averages both directions.

Time in the air by direction, 2025

Direction	Average minutes in the air	Flights
New York to Chicago	116.7	23,484
Chicago to New York	98.3	23,513

Fly or drive

Driving is about 854 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 254 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 103% more than the 125 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (85 kg each, and 63 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 337 kg per vehicle.

CO2 per person, New York to Chicago. Driving figures divide one car's emissions between the people in it. See flying vs driving for other trip lengths.

Flights are listed under the airline that operates them, so regional flying appears under the regional. How the CO2 and drive figures are worked out is in the methodology.

What to take from it

'Chicago' is mostly O'Hare, which handles 89% of the passengers. Going west costs 18 more minutes than coming back, 19% longer, about 21 kg more per passenger, one of the largest wind penalties among the 15 busiest routes.

If you have the choice, a full-size jet is the lower-carbon option on this route, and the regional jets run at about twice the figure. With three people in a car, the 854-mile drive is 85 kg each, 32% below the flight.

Routes with shared cities or nearby CO2 per mile

Airports on this route: O'Hare International Airport, LaGuardia Airport, Newark Liberty International Airport, Midway International Airport, John F. Kennedy International Airport.

Airport and airline references

Source: US Bureau of Transportation Statistics (BTS), T-100 traffic and Schedule T-2 fuel filings; US EPA transport emission factors. See the methodology.

See all routes, or how the airlines compare overall on the airline pages.