Chicago to Philadelphia

Between Chicago and Philadelphia, 1.6 million passengers flew nonstop in 2025, on 12 thousand flights of about 675 miles and 1.6 hours in the air. The average passenger accounted for about 112 kg of CO2 from the fuel burned, from 85 kg on Frontier Airlines to 120 kg on American Airlines.

112 kgCO2 per passenger, average
675 milesabout 1.6 hours in the air
1.6 millionpassengers in 2025
82%of seats filled

CO2 per passenger, airline by airline

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

Chicago to Philadelphia by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
American Airlines	45%	5.4	Boeing 737-800, Airbus A319	164	82%	120
United Airlines	26%	3.2	Boeing 737-800, Boeing 737-900ER	162	82%	114
Southwest Airlines	24%	2.9	Boeing 737 MAX 8, Boeing 737-700	165	83%	98
Frontier Airlines	4%	0.5	Airbus A320neo, Airbus A321neo	198	78%	85

What explains the differences

It's number 96 of the 100 busiest city pairs by passengers, and number 67 for the lowest CO2 per mile flown (0.17 kg per passenger-mile, number 1 being the lowest). A typical route of 675 miles in this set comes out at about 112 kg, so this one is close to that.

The flights use more than one pair of airports: ORD to PHL (74%), MDW to PHL (26%). The figures here cover all of them.

The airlines on this route differ by 41% per passenger. Frontier Airlines burned 1,350 gallons per flight and 154 passengers on each, and American Airlines 1,661 gallons and 135 passengers. Fuel burned per flight explains about 61% of the gap and the number of passengers on each flight the other 39%. Frontier Airlines flew 78% full here against 82% for American Airlines, flying mostly Airbus A320neo against Boeing 737-800.

For comparison, the EPA default factor for a flight of this length (0.129 kg per passenger-mile) would give 87 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 28% higher.

2019 compared with 2025

In 2019 the route carried 1.7 million passengers on 13 thousand flights. In 2025 it carried 1.6 million, down 7%, on 12 thousand flights, down 11%. The average flight had 161 seats then and 165 now, and 80% of them were filled against 82%.

CO2 per passenger was 119 kg in 2019 and 112 kg in 2025, down 6.4%. Fuel burned per flight was down 2.1% (1,583 gallons to 1,550) and passengers per flight were up 4.6% (129 to 135). The distance flown was about the same (675 miles then, 675 now).

American Airlines led in both years, with 48% of passengers in 2019 and 45% in 2025. American Airlines lost the most, 48% to 45%. Frontier Airlines didn't have 1% of the passengers in 2019 and now carries 4%.

Airline by airline, Southwest Airlines went from 119 kg to 98 kg per passenger (154 seats per flight to 165, main aircraft Boeing 737-700 then and Boeing 737 MAX 8 now); American Airlines went from 119 kg to 120 kg per passenger (174 seats per flight to 164, main aircraft Airbus A321 then and Boeing 737-800 now).

Chicago to Philadelphia, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	1,742	1,624
Flights (thousands)	13.5	12.0
Seats filled	80%	82%
Gallons of fuel per flight	1,583	1,550
kg CO2 per passenger	119	112

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.

Chicago to Philadelphia and back: time in the air

Flights from Philadelphia to Chicago spent 106 minutes in the air on average in 2025, against 90 minutes from Chicago to Philadelphia: 16 minutes longer, 18% 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 947 gallons per flight hour, those extra minutes cost about 257 gallons per flight, which is about 1.9 gallons or 19 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
Philadelphia to Chicago	106.4	5,980
Chicago to Philadelphia	90.1	6,014

Fly or drive

Driving is about 790 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 235 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 110% more than the 112 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (78 kg each, and 59 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 311 kg per vehicle.

CO2 per person, Chicago to Philadelphia. 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.

Routes with shared cities or nearby CO2 per mile

Airports on this route: O'Hare International Airport, Midway 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.