„Fast
racts
U.S.Transportation Sector
Greenhouse Gas Emissions
1990-2017
United States
Environmental Protection
M m Agency
Office of Transportation and Air Quality
EPA-420-F-19-047
June 2019

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Mobile Sources
Transportation
Non-Transportation Mobile
Highway Vehicles
Agricultural Equipment
Aircraft
Construction & Mining Equipment
Ships & Boats
Lawn & Garden Equipment
Rail
Logging Equipment
Lubricants
Recreational Equipment
Pipelines1

Transportation Emissions of the United States
The transportation sector is one of the largest contributors to anthropogenic greenhouse gas
(GHG) emissions in the United States. According to the Inventory of US. Greenhouse Gels
Emissions and Sinks 1990-2017 (the Inventory), the national inventory that the U.S. prepares
annually under the United Nations Framework Convention on Climate Change (UNFCCC),
the transportation sector accounted for the largest portion (29%) of total U.S. GHG emissions
in 2017. Cars, trucks, commercial aircraft, and railroads, among other sources, all contribute
to transportation end-use sector emissions. Within the sector, light-duty vehicles (including
passenger cars and light-duty trucks) were by far the largest category, with 59% of GHG
emissions, while medium- and heavy-duty trucks made up the second largest category, with
23% of emissions. Between 1990 and 2017, GHG emissions in the transportation sector
increased more in absolute terms than any other sector (i.e. electricity generation, industry,
agriculture, residential, commercial), due in large part to increased demand for travel.
Greenhouse gas emissions from transportation sources include carbon dioxide (C02), methane
(CH4), nitrous oxide (N20), and various hydrofluorocarbons (HFCs). C02, CH4, and N20 are
all emitted via the combustion of fuels, while HFC emissions are the result of leaks and end-
of-life disposal from air conditioners used to cool people and/or freight.2
When including emissions from non-tictnsportcttion mobile sources such as agricultural, lawn
and garden, and construction equipment, mobile sources constituted 32% of total U.S. GHG
emissions in 2017.
Electric Power
28%
Transportation
29%
Aircraft
Medium- and
Heavy-Duty Trucks
23%
Residential
5%
Commercial
6%
Share of U.S. GHG Emissions
by Sector, 20 1 73'4
Note: Totals may not add to 100% due to rounding.
Share of U.S. Transportation Sector
GHG Emissions by Source, 20174'5
Note: Totals may not add to 100% due to rounding.
Share of U.S. Transportation Sector
GHG Emissions by Gas, 20174
Note: Totals may not add to 100% due to rounding.
11 Pipeline emissions in the transportation sector include only C02 from the combustion of natural gas at compressor stations that power
natural gas pipelines, not emissions from electricity use, non-C02 gases, or other types of pipeline equipment. Not that natural gas pipeline
compressor stations are stationary equipment that are included in the transportation sector, but are not considered mobile sources.
2 C02 emissions from the combustion of biofuels are not directly included in the energy sector contribution (which includes the contribution
of transportation and non-transportation mobile sources) to U.S. totals in the Inventory; instead, net carbon fluxes from changes in biogenic
carbon reservoirs are accounted in the estimates for Land Use, Land-Use Change, and Forestry in the Inventory. See Page 4 for more
information on the Inventory.
3	For presentation purposes, emissions from territories which constitute less than 1% of the total U.S. GHG emissions, are not shown in
this chart, although they are included in the total emissions used to calculate the percentage share of emissions from each sector. See
Table ES-6 in the Executive Summary of the Inventory for official data. See page 4 for more information on the Inventory.
4	"Transportation" emissions in these pie charts include C02, N20, CH4, and HFCs from transportation sources like highway vehicles,
aircraft, ships and boats, rail, pipelines and lubricants. They do not include emissions from non-transportation mobile sources such as
agriculture and construction equipment.
5	"Other" sources include buses, motorcycles, pipelines, and lubricants.

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U.S.Transportation GHG Emissions
(Tg C02 Equivalent)
Change from
1990 to 2017
Source

1990
2000
2005
2010
2015
2016
2017
Absolute
Percent
On-Road Vehicles6
1,206.8
1,545.7
1,648.0
1,516.6
1,525.4
1,553.4
1,558.6
351.8
29.2
Light-Duty Vehicles
966.3
1,184.6
1,234.1
1,106.9
1,086.4
1,106.4
1,098.0
131.7
13.6
Passenger Cars
639.6
681.2
693.8
766.0
762.0
772.6
770.7
131.1
20.5
Light-Duty Trucks
326.7
503.3
540.2
340.8
324.5
333.8
327.3
0.5
0.2
Motorcycles
1.7
1.8
1.6
3.6
3.7
3.9
3.8
2.1
119.2
Buses
8.5
11.0
12.2
15.9
19.8
19.5
20.4
11.9
140.9
Medium- and Heavy-
Duty Trucks
230.3
348.3
400.1
390.2
415.5
423.6
436.5
206.2
89.5
Aircraft
189.2
199.4
193.6
154.8
160.5
169.0
174.8
-14.3
-7.6
Commercial Aviation
110.9
140.6
134.0
114.4
120.1
121.5
129.2
18.3
16.5
Military Aircraft
35.3
22.9
19.5
13.7
13.6
12.4
12.3
-23.0
-65.1
General Aviation
42.9
35.9
40.1
26.7
26.8
35.1
33.3
-9.6
-22.4
Ships and Boats
47.4
66.0
45.7
45.2
34.1
41.3
44.4
-3.1
-6.5
Rail
35.8
42.6
46.1
39.2
40.4
37.2
38.4
2.5
7.1
Pipelines7
36.0
35.5
32.4
37.3
38.5
39.2
41.4
5.4
15.0
Lubricants
11.8
12.1
10.2
10.4
11.0
10.4
9.6
-2.3
-19.1
Transportation Total
1,527.1
1,901.2
1,976.0
1,803.5
1,809.9
1,850.5
1,867.1
340.1
22.3
U.S. Non-Transportation Mobile GHG Emissions
Non-Transportation
Mobile8
170.3
179.9
223.8
202.3
187.9
190.5
196.7
26.4
15.5
Agricultural
Equipment
44.6
40.4
51.6
47.1
41.3
40.4
40.0
-4.5
-10.2
Construction
Equipment
50.4
58.3
77.5
66.2
57.7
60.6
65.7
15.3
30.3
Other Non-
Transportation Mobile
75.3
81.2
94.8
89.1
88.8
89.5
91.0
15.7
20.8
Non-Transportation +
Transportation Total
1,697.3
2,081.1
2,199.8
2,005.8
1,997.8
2,040.9
2,063.8
366.5
21.6
U.S.Transportation GHG Emissions by Gas, 2017
(Tg C02 Equivalent)
Source
o
o
ch4
n2o
HFCs
Total
Percent
On-Road Vehicles6
1,508.8
1.0
12.1
36.7
1,558.6
75.5
Light-Duty Vehicles
1,055.4
0.7
11.3
33.3
1,100.6
53.3
Passenger Cars
750.6
0.5
8.2
11.4
770.7
37.3
Light-Duty Trucks
304.8
0.2
3.1
19.2
327.3
15.9
Motorcycles
3.7
0.0
0.0
0.0
3.8
0.2
Buses
19.7
0.2
0.0
0.4
20.4
1.0
Medium- and Heavy-
Duty Trucks
430.0
0.1
0.8
3.1
433.9
21.0
Aircraft
173.2
0.0
1.6
0.0
174.8
8.5
Commercial Aviation
128.0
0.0
1.2
0.0
129.2
6.3
Military Aircraft
12.2
0.0
0.1
0.0
12.3
0.6
General Aviation
33.0
0.0
0.3
0.0
33.3
1.6
Ships and Boats
40.3
0.3
0.5
3.3
44.4
2.1
Rail
37.9
0.1
0.3
0.1
38.4
1.9
Pipelines7
41.4
0.0
0.0
0.0
41.4
2.0
Lubricants
9.6
0.0
0.0
0.0
9.6
0.5
Transportation Total
1,811.1
1.4
14.5
40.1
1,867.1
90.5
Rail Electricity
3.37
0.00
0.06
0.00
3.44
NA
U.S. Non-Transportation Mobile GHG Emissions by Gas, 2017
Change in GHG Emissions by Sector: 1990-2017
¦ Light Duty Vehicles ¦ Medium-and Heavy-Duty Trucks ¦ Aircraft BRail ¦ Non Transportation Mobile Sources BAN Other Transportation Sources ¦ Ships and Boats
Non-Transportation
Mobile8
192.5
1.8
2.4
0.0
196.7
9.5
Agricultural
Equipment
39.4
0.1
0.5
0.0
40.0
1.9
Construction
Equipment
64.4
0.4
0.9
0.0
65.7
3.2
Other Non-
Transportation Mobile
88.6
1.3
1.0
0.0
91.0
4.4
Non-Transportation +
Transportation Total
2,003.6
3.2
16.9
40.1
2,063.8
100.0
GHG emissions and vehicle miles traveled (VMT) estimates for on-road vehicles presented in the Inventory are
based on Federal Highway Administration (FHWA) data. In 2011 FHWA changed its methods for estimated VMT
and related data. These methodological changes included how vehicles are classified, moving from a system
based on body-type to one that is based on wheelbase. These changes were first incorporated for the 1990
through 2008 Inventory and apply to the 2007 to 2017 time period. This resulted in large changes in VMT data
by vehicle class, leading to a shift in emissions among on-road vehicle classes. This change in vehicle classifica-
tion has moved some smaller trucks and sport utility vehicles from the light truck category to the passenger
vehicle category in this Inventory.
Includes only C02 from natural gas used to power natural gas pipelines; does not include emissions from
electricity use or non-C02 gases.
Note: non-transportation C02 emissions estimates are presented here and in Annex 3.2 of the Inventory for
informational purposes, but these emissions are officially accounted for in other energy sectors in the Inventory
(i.e., industrial, residential, commercial sectors) using a different method. See Annex 3.2, Supplemental
Information on Transportation-Related GHG Emissions, of the Inventory for more information.
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
2009 2010 2011 2012 2013 2014 2015 2016 2017

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2017 Fuel Consumption

Volume
(billion gallons unless
otherwise specified)
Energy (Tbtu)
C02 (Tg)
MOTOR GASOLINE
128.9
15,999.5
1,232.9
Transportation9
Light-Duty Vehicles
116.8
14,517.1
1,035.6
Passenger Cars
84.0
10,447.6
745.3
Light-Duty Trucks
32.7
4,069.6
290.3
Medium- and Heavy-Duty Trucks
4.7
578.6
41.3
Motorcycles
0.4
52.0
3.7
Buses
0.1
12.6
0.9
Recreational Boats
1.2
150.6
10.7
Non-Transportation10
Agricultural Equipment
0.2
20.2
1.4
Construction Equipment
0.4
45.1
0.0
Other Non-Transportation Mobile
5.2
623.2
139.2
DISTILLATE FUEL
59.4
8,167.9
608.1
Transportation9
Light-Duty Vehicles
1.8
252.3
18.7
Passenger Cars
0.4
59.3
4.4
Light-Duty Trucks
1.4
193.0
14.3
Buses
1.8
242.1
17.9
Medium- and Heavy-Duty Trucks
38.2
5,250.0
388.3
Recreational Boats
0.3
38.2
2.8
Ships and Boats
1.0
138.4
10.2
Rail
3.7
511.9
37.9
Non-Transportation10
Agricultural Equipment
3.7
512.3
37.9
Construction Equipment
6.0
821.5
64.4
Other Non-Transportation Mobile
2.9
401.1
30.0
RESIDUAL FUEL OIL
1.5
219.3
16.5
Ships and Boats
1.5
219.3
16.5
JET FUEL
17.6
2,378.1
171.8
Commercial Aircraft
13.5
1,819.2
128.0
General Aviation Aircraft
3.0
402.8
31.5
Military Aircraft
1.2
156.1
12.2
AVIATION GASOLINE
0.2
20.9
1.4
General Aviation Aircraft
0.2
20.9
1.4

Volume
(billion gallons unless
otherwise specified)
Energy (Tbtu)
C02 (Tg)
NATURAL GAS (billion cubic feet)
816.4
846.6
44.8
Transportation



Passenger Cars
0.1
0.1
0.0
Light-Duty Trucks
0.2
0.2
0.0
Medium- and Heavy-Duty Trucks
0.7
0.8
0.0
Buses
14.8
15.3
0.8
Pipelines
754.4
782.3
41.4
Non-Transportation10



Agricultural Equipment
1.5
1.6
0.1
Construction Equipment
6.0
6.2
0.3
Other Non-Transportation Mobile
38.7
40.1
2.1
LPG
2.6
214.3
13.2
Transportation



Passenger Cars
0.0
0.2
0.0
Light-Duty Trucks
0.0
1.3
0.1
Medium- and Heavy-Duty Trucks
0.1
6.5
0.4
Buses
0.0
2.0
0.1
Non-Transportation10



Agricultural Equipment
0.0
0.0
0.0
Construction Equipment
0.0
2.1
0.1
Other Non-Transportation Mobile
2.4
202.2
12.5
LUBRICANTS
0.0
1.0
9.6
Total11
216.4
27,847.6
2,098.2

BIOFUELS12



Transportation
Biodiesel
2.0
253.3
18.7
Ethanol
13.4
1,135.2
77.7
9	Fuel consumption, energy, and C02 emissions from transportation sources using motor gasoline and distillate fuel exclude contribu
tionsfrom biofuels.
10	Non-transportation mobile fuel consumption, energy, and C02 are estimated based on the Nonroad component of EPA's MOVES
model (see www.epa.gov/moves/nonroad-model-nonroad-engines-equipment-and-vehicles). Because the fuel composition in the
MOVES-Nonroad model is intended to reflect real-world usage, these estimates may include low-level ethanol blends. Note that these
estimates are presented here and in Annex 3.2 of the Inventory for informational purposes, but that non-transportation mobile source
C02 emissions are officially accounted for in other energy sectors in the Inventory (e.g., the industrial sector) using a different method
and do not include emissions from biofuels.
11	Total Volume is the sum of physical (billion) gallons of fuel; because natural gas volumes are reported as million cubic feet, natural
gas volumes are converted to billion gallons of gasoline equivalent for the Total Volume (billion gallons) sum in this table.
12	Biofuels are presented as line items below the total for informational purposes only, in line with IPCC methodological guidance
and UNFCCC reporting obligations. Biofuel estimates only reflect transportation sources and do not include biofuels used in non-
transportation mobile sources, e.g., ethanol used in commercial or industrial applications. C02 emissions from the combustion of
biofuels are not directly included in the energy sector contribution (which includes the contribution of transportation sources) to U.S.
totals in the Inventory; instead, net carbon fluxes from changes in biogenic carbon reservoirs are accounted in the estimates for
Land Use, Land-Use Change, and Forestry in the Inventory. See page 4 for more information on the Inventory

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Additional Information
Data Sources for This Document
The source for all data in this document is the Inventory of US. Greenhouse Gels Emissions
and Sinks 1990-2017 (EPA 2019). The U.S. Environmental Protection Agency prepares
the inventory annually to fulfill the U.S. commitment under the United Nations Framework
Convention on Climate Change (UNFCCC), using calculation methods that are consistent
with guidelines from the Intergovernmental Panel on Climate Change (IPCC). Complete
information on the inventory is available at: www.epa.gov/ghgemissions/inventory-us-
greenhouse-gas-emissions-and-sinks. The inventory methods and assumptions related to
transportation and non-transportation mobile sources are available in the main body of the
Inventory as well as Annex 3.2 of the Inventory.
Inventory Definitions of Selected Transportation Categories13
Light-Duty Vehicles: passenger cars and light-duty trucks
Passenger Cars:14 automobiles used primarily to transport 12 people or less. In
2017, passenger cars traveled a total of 2,220,801 million vehicle miles.
Light-Duty Trucks:14 vehicles used primarily for transporting light-weight
cargo or which are equipped with special features such as four-wheel drive
for off-road operation. In the U.S., this category also includes many vehicles
that primarily transport passengers such as sport utility vehicles (SUVs) and
minivans. The gross vehicle weight rating (GVWR) normally ranges around
8,500 pounds or less. GVWR is the maximum weight a vehicle is designed to
carry when passengers, fuel, cargo, and any other additions to the vehicle are
accounted for. In 2017, light-duty trucks traveled a total of 656,578 million
vehicle miles.
Medium- and Heavy-Duty Trucks:14 vehicles with GVWR of more than
around 8,500 pounds. In the Inventory, single unit trucks and combination
trucks represent the medium- and heavy-duty truck category, including tractor-
trailers and box trucks used for freight transportation. In addition, this category
includes some vehicles that are not typically used for freight movement such as
service and utility trucks. In 2017, medium- and heavy-duty trucks traveled a of
314,820 million vehicle miles.
Pipelines: systems that transport liquids, gases, or slurries through either
above or below ground pipes. In the Inventory, the pipelines category includes
emissions from the combustion of natural gas used to power pumps and other
distribution equipment, while leaks and other emission sources from pipelines
are assigned to the natural gas systems category.
|lii*L
Emissions Metrics
A teragram (Tg) is equal to 1 million metric tons.
Greenhouse gas (GHG) emissions are measured in this document in terms of teragrams
of "carbon dioxide equivalent" (C02 Eq); an "equivalent" refers to the Global Warming
Potential (GWP) of a greenhouse gas. GWP values are determined based on the chosen time
horizon and properties of the gas, such as its ability to absorb radiation and its atmospheric
lifetime. C02 has a GWP of "1"; all other greenhouse gases have GWP values relative to
that of COr For example, methane (CH4) has a radiative forcing value or GWP of 25, which
means that releasing one ton of CH4 is equivalent to releasing 25 tons of C02.
The data in this document is based on the 100-year time horizon GWP values from the
IPCC's Fourth Assessment Report15, in accordance with UNFCCC reporting guidelines for
national GHG inventories. More information on greenhouse gases and GWP is available at:
www.epa.gov/ghgemissions/overview-greenhouse-gases.
The data used to estimate emissions for specific transportation categories may not directly align with the
Inventory's definition of the categories; both the data and Inventory definitions may also differ from EPA's
regulatory definitions for the same categories.
14	GHG emissions and vehicle miles traveled (VMT) estimates for on-road vehicles presented in the Inventory
are based on FHWAdata. In 2011 FHWA changed its methods for estimated VMT and related data. These
methodological changes included how vehicles are classified, moving from a system based on body-type to one
that is based on wheelbase. These changes were first incorporated for the 1990 through 2008 Inventory and apply
to the 2007 to 2017 time period. This resulted in large changes in VMT data by vehicle class, leading to a shift in
emissions among on-road vehicle classes. This change in vehicle classification has moved some smaller trucks
and sport utility vehicles from the light truck category to the passenger vehicle category in this Inventory.
15	See www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf.
4

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