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A Roadmap for the Last Gas Tax Increase

The Brief
  • The federal Highway Trust Fund, which supports the construction and maintenance of our nation’s highways and transit systems, is facing a cash flow crisis.

  • To fix the fund with bipartisan support, we propose: one last increase in fuel user fees; policies to strengthen the user-pay, user-benefit model; a gradual transition to a user fee based on vehicle miles traveled; and the return of congressionally directed spending.

  • Our roadmap is the most politically viable and fiscally responsible solution to pay for the next federal surface transportation reauthorization bill and meet our nation’s transportation needs for the next decade.


DOTDepartment of Transportation
FAST ActFixing America’s Surface Transportation Act of 2015
HTFHighway Trust Fund
MPGMiles per gallon
RUCRoad usage charge
SAFETEA-LUSafe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users Act of 2005
STSFASurface Transportation System Funding Alternatives
TEA-21Transportation Equity Act for the 21st Century of 1998
VMTVehicle miles traveled
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The Highway Trust Fund (HTF) has historically embodied a user-pay, user-benefit model, in which drivers pay a tax on the gasoline they buy and, in return, the federal government doles out the attendant revenue to support a national, connected transportation network. This system provides for a clear nexus between who pays and who benefits, though having safe, modern transportation systems does benefit more than just drivers.

Excise fees on motor fuels—18.4 cents per gallon of gas and 24.4 cents per gallon of diesel fuel—are the HTF’s primary revenue source. However, those fees have not increased since 1993 and were not indexed to keep pace with inflation. As such, fund revenues have lost over 40% of the purchasing power they had, as the costs of labor and construction materials have risen. At the same time, while Americans are collectively driving more than ever before, improvements in fuel efficiency have cut down on the amount of gas Americans consume.

Trust fund spending has exceeded annual revenues from fuel taxes every year since 2000. Only with general revenue transfers from the Treasury Department, secured in the Fixing America’s Surface Transportation (FAST) Act, will the fund meet its obligations through 2020, but not after.

Congress could pay for projected highway and transit spending by simply raising the federal tax rate on gasoline and diesel fuel. Had fuel taxes been indexed to inflation in 1993, they would be about 15 cents higher today. Such an increase alone would enable the HTF to meet its obligations for the next decade and beyond.

However, Congress has long evaded the politically daunting task of raising transportation user fees. Members on both sides of the aisle have their reasons and—with rising electric and hybrid vehicle ownership—relying predominately on the gas tax is not an equitable or sustainable long-term solution. This paper aims to overcome the political challenges that have blocked progress for too long. We offer a bipartisan path forward with four key recommendations to sustainably fund federal transportation programs and break the political logjam:

  1. Increase fuel user fees for the last time and index them to inflation.
  2. Strengthen the user-pay, user-benefit model.
  3. Prepare for the transition to user fee based on vehicle miles traveled.
  4. Restore congressionally directed spending with safeguards.

Status of the Highway Trust Fund

Federal trust funds are essentially accounting mechanisms to track incoming receipts (i.e., tax revenues) that are earmarked for a specific spending purpose (i.e., outlays or expenditures). The HTF records inflows from revenues collected through (1) excise taxes/fees on the sale of motor fuels, trucks and trailers, and truck tires; (2) taxes on the use of certain kinds of vehicles; and (3) interest credited to the fund. The trust fund records cash outflows for spending on designated highway and transit projects, mostly in the form of grants to state and local governments.

Excise fees on motor fuels, the HTF’s primary revenue source, were increased in 1993 to 18.4 cents per gallon of gasoline and 22.4 cents per gallon of diesel, but were not indexed to keep pace with inflation thereafter. As such, the gas tax has lost over 40% of the purchasing power it had in 1993, as the costs of labor and construction materials have risen and fuel efficiency improvements have cut down on the amount of gas Americans consume.1 Importantly though, all of the revenue raised by this user-based fee is spent on roads, bridges, transit, and surface transportation programs and projects.

Previous highway reauthorization bills, beginning with TEA-21 in 1998 and SAFETEA-LU in 2005, did little to put the HTF on the right fiscal path. They salvaged the fund with short-term fixes, but enabled the gradual decoupling of revenue and spending. As a direct result, the HTF has received $140 billion in bailouts from the Treasury Department’s general fund since 2008 to cover revenue shortfalls. As federal budget deficits grow, however, it will be increasingly difficult to bail out the HTF with general revenues.

Unified Highway Trust Fund Accounts Under the CBO Baseline

Source: Congressional Budget Office (CBO)

The HTF’s highway and mass transit accounts combined would have exceeded incoming revenue by $12.3 billion in fiscal year 2019 were it not for general transfers. Deficits between HTF spending and revenues will increase steadily to $25.9 billion in fiscal year 2029.<2 This will run the balance of the fund down to zero by 2022 and result in a cumulative revenue shortfall of $176 billion over the next 10 years.3Over the 10-year budget window and beyond, the revenue generated from fees on gasoline are expected to diminish with increasing electric and hybrid vehicle ownership and rising fuel efficiency.

By one estimate, increasing fuel efficiency will cost states and the federal government as much as $20.8 billion per year by 2025, with losses rising to more than $33 billion by 2030 and almost $45 billion by 2040.4 The average fuel efficiency of new vehicles sold in the United States is 24.9 miles per gallon, a notable increase from the 2005 average of 20 mpg.

California, followed by 14 states and the District of Columbia, have committed to fuel efficiency goals requiring all new vehicles sold to average about 50 mpg by 2025. Together, these states annually account for nearly 40% of new vehicle purchases. These higher fuel efficiency standards could become the de facto standard for the country, as automakers aim to market similar vehicles to all states. While the Trump administration has sought to freeze mileage standards nationwide at 37 mpg from 2020 to 2026, rising electric vehicle ownership and voluntary improvements in fuel economy may ultimately render moot the protracted legal and regulatory battle that has resulted.

Estimated State and Federal Fuel Tax Revenues (2017 Dollars, Assuming Nominal $0.47/Gal. Combined Average Tax)

Source: CDM Smith

There is currently no federal mechanism for electric vehicle owners—who do not need to buy gas—to contribute to the HTF. By not paying any user-based fee, electric vehicles reduce HTF revenues by $250 million annually, an amount expected to rise with increased ownership.5 That foregone revenue is highly concentrated in a handful of states and is highly regressive, as most electric vehicles are driven by high-income households.

In 2018, over 650,000 vehicles were sold in the United States with some form of electric or hybrid engine capacity and ownership is rising. Plug-in and battery electric vehicle sales jumped 63% from 2017 to 2018.6 They are still a relatively niche choice for the average car purchaser, making up only 2% of all light vehicles sold in 2018. Yet some estimates suggest electric and hybrid vehicles could comprise more than 60% of the purchase market by 2030. The results from a recent survey from AAA appear to support this trend, reporting that 20% of Americans are considering an electric vehicle for their next purchase.7

Increased ownership and use of electric and more fuel-efficient vehicles will mean less and less revenue to the HTF without reform in Congress.

Political Challenges

While a vote now to increase and index the gas tax would forestall similar votes in the future, there are political obstacles that must be overcome before members of Congress will be willing to walk down that plank. To lay the groundwork for an increase, Congress will need to address several issues:

Raising taxes and fees is unpopular. There is no denying that half of Congress views tax increases as anathema. However, a recent poll by BPC and the Business Roundtable found a majority of respondents would support a gas tax increase of at least 10 cents if it would result in less time spent in traffic or less money spent on car repairs. This “bread and butter” argument could provide the political cover politicians need. If drivers are going to be asked to pay more, they must be shown the tangible benefits their tax dollars will bring. In the absence of congressional action, 31 states and the District of Columbia have enacted legislation that increases or may increase overall state gas taxes since 2013.8 These efforts further illustrate how voters can be swayed to support revenue increases despite their purported unpopularity. Fuel costs should also be put in context of other consumer spending and patterns. Although the average American spends approximately $2,109, or $175 per month, on gas and motor oil, prices have been relatively stable.9 From 2009 to 2019, prices increased much faster for water and sewer bills (57%), cable/TV (33%), trash collection (28%), and electricity (11%) than the 2% rise American consumers have seen in gas prices.10

State-Level Efforts to Increase Gas Taxes

Combined local, state, and federal cost of gas in cents/gallon, as of July 2019

  • Greater than 50 cents
  • 40 - 50 cents
  • Less than 40 cents
  • Greater than 50 cents
  • 40 - 50 cents
  • Less than 40 cents
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Rhode Island
South Carolina
South Dakota
West Virginia

Gas taxes and user fees are regressive. While some perceive the gas tax to be regressive, the lowest 20% of the population spends about 4% of their income on gas taxes compared to 3% for the wealthiest 20% of the population.11 While this is sufficiently regressive to justify opposition from some members, their concerns may be addressed by looking more holistically at assistance programs for low-income households and enhancing programs that support equitable and affordable access to transportation options, including transit.

Not everyone pays their fair share. Fairness is critically important in building public and political support for user fees. While the gas tax has traditionally followed the user-pay, user-benefit model, it does face a few challenges that undermine that perception. For one, electric vehicle owners do not pay gas taxes and yet, they use roads. At the same time, the federal government also provides a tax credit to encourage the purchase of electric vehicles. Some members, particularly those representing rural and disadvantaged communities where electric car ownership is less common, want this inequity resolved. Additionally, some HTF dollars flow to transit systems and other projects like bike lanes, creating a perception that drivers pay for transit systems and non-highway infrastructure from which they derive little to no benefit. Though this thinking ignores how supporting driving alternatives can help relieve heavily trafficked highways and benefit the environment, it is difficult to combat. Our proposals to fix the HTF work to combat these perceptions and promote fairness.

A gas tax increase overburdens “responsible states.” As mentioned, 31 states and the District of Columbia have enacted legislation that increases or may increase overall state gas taxes since 2013.12 Some members of Congress from these jurisdictions fear the political backlash of further increasing the burden borne by their constituents, given these recent increases and already-high taxes. This line of thinking ignores how increased federal funding would allow states to redistribute spending to other priorities. Others believe the states have proven themselves capable of stepping up to address their own needs without the federal government. Yet assessments of infrastructure nationwide continue to show a significant need for increased investment to bring infrastructure into a state of good repair.

Our recommendations reflect and respond to these issues and others, as they have clearly halted progress on this issue for years.

Policy Recommendations

Our roadmap recommends Congress:

  1. Increase fuel user fees for the last time and index them to inflation.
  2. Strengthen the user-pay, user-benefit model.
  3. Prepare for the transition to a user fee based on vehicle miles traveled.
  4. Restore congressionally directed spending, with safeguards.

Increase fuel user fees for the last time and index them to inflation.

A static gas tax, unadjusted to keep pace with inflation, can meet fewer infrastructure needs over time and will put increasing pressure on Congress to find offsets in the budget or deficit-spend—the latter being fiscally irresponsible. In total, Congress must find $176 billion in the budget to cover projected HTF revenue shortfalls over the next 10 years.

To boost transportation funding, finally tackle deferred maintenance, sustainably pay for needed investments, and buy time to transition to a user fee based on vehicle miles traveled, fuel user fees should be increased by at least 15 cents and indexed to inflation. This is the only short-term option that will adequately cover all near-term needs and maintain the user-pay principle. We estimate an increase (on gasoline, diesel, and special fuels) of 15 cents before fiscal year 2021 and indexation would bring in about $291 billion in additional revenue to cover HTF spending over the next 10 years. This amounts to almost $30 billion in extra revenue per year to cover projected average annual shortfalls of $20 billion, providing some wiggle room to phase in these increases if more politically palatable.

Strengthen the user-pay, user-benefit model.

The HTF provides for a nexus between who pays and who benefits from the fund, though it does not follow a direct 1:1 user-pay, user-benefit model. Starting in 1970, just 14 years after the creation of the trust fund, Congress began expanding the list of eligible projects to include transit projects, despite only collecting revenue from a variety of vehicle-related taxes.

States also are not allocated funds strictly by a dollar-in, dollar-out model, but by intricate formulas that Congress has avoided adjusting in recent years. In fact, three states—Texas, Colorado, and South Carolina—received fiscal year 2020 formula funding that is less than their shares of the revenue previously paid into the HTF Highway Account. Other states receive far more than their payments. For example, Hawaii (206%), Montana (256%), Rhode Island (300%), Vermont (305%), and Alaska (626%), plus the District of Columbia (892%), have received formula funding that far exceeds 100% of their HTF Highway Account payments.13

While a binary, 1:1 funding system would be difficult to achieve and would undermine the ability of federal funds to meet a variety of local, state, and national transportation priorities, policymakers should seek to ensure that those who benefit from HTF spending are contributing something. To that end, Congress should:

  • Roughly synchronize spending with user tax/fee receipts;
  • Periodically analyze all HTF user taxes and fees to ensure costs are fairly allocated to different classes of system users;
  • Ensure more beneficiaries of the HTF pay into it by, for example, reinstating the diesel tax for passenger trains, eliminating reduced user fees on fuel for intercity and local buses, and levying a modest user fee on bicycle tires; and
  • Support electric vehicle ownership while ensuring their drivers contribute to the HTF.

The Role of Income in Ownership and Interest in Electric Vehicles (EVs)

Data Coalition in 2012

Percent of people expecting to buy EV for next vehicle, by income

People with incomes over $100,000 are more likely to consider buying EV Source: American Petroleum Institute, National Conference of State Legislatures
Percentage of people expecting to buy EV for next vehicle
Less than 50,000 21 %
50,000-100,000 19 %
Over 100,000 31 %

Given rising electric vehicle ownership, its impact on HTF revenues, and concerns about our changing climate, harmonizing support for electric vehicle ownership with a system of dedicated highway spending that is dependent on a user-paid gas tax is among the most critical challenges to strengthening the user-pay, user-benefit model. We believe there is bipartisan appetite for policies that improve the electric vehicle tax credit’s targeting and effectiveness, stimulate more market demand, get the most fuel-inefficient vehicles off our roads, and find a way to ensure the drivers of electric and hybrid vehicles contribute to the HTF.

While federal income tax credits have resulted in a 29% increase in electric vehicle sales, research has shown that 70% of the credits were obtained by households—typically with higher incomes—that would have bought an EV without the credits.14Therefore, reform should entail:

  • Limiting the tax credit for electric vehicle purchases to low- and middle-class taxpayers;
  • Expanding the credit with any projected savings from limiting credit eligibility; and
  • Enacting either a modest national fee on electric vehicle purchases or an electric vehicle battery tax to ensure these drivers are contributing revenue to the HTF, which supports the continued upkeep and modernization of our nation’s critical transportation systems.

Prepare for the transition to a user fee based on vehicle miles traveled.

In 2009, the congressionally chartered National Surface Transportation Financing Commission called for the immediate planning of a transition away from fuel user fees and the creation of a national, user-based funding system, based on vehicle miles traveled (VMT), road usage charges (RUC), and other user fees and taxes.15Under the commission’s plan, a comprehensive system would be ready by 2020. While progress has been made since the commission’s report in studying and piloting road usage charge systems, Congress has not dedicated enough resources to prepare for such a transition.

Fortunately, Congress does not need to reinvent the wheel. The Federal Highway Administration’s Surface Transportation System Funding Alternatives (STSFA), authorized under the FAST Act through 2020, has already begun administering $95 million in competitive grants to test new ways to finance highway and bridge projects. Awarded projects have included state-level evaluations of various mileage-based and RUC systems, including for trucks and automated vehicles, and the implementation and operation of such technologies at a regional level. Current grants provide 50% of a project’s funding and require at least 50% to come from non-federal sources.

With rising ownership of electric and more fuel-efficient vehicles, transitioning from gas taxes to a user charge based on miles traveled for all vehicles will be fundamental to sustaining the user-pay, user-benefit system. With support from STSFA grants, a few state-led pilots have been able to begin experimenting with such a replacement.16 However, even the two largest of these pilots—in California and Oregon—included just 5,000 participating drivers. Today, only 10 states have passed legislation to allow their respective departments of transportation to study the RUC concept. More work must be done before this model can be fully viable and seamlessly implemented at a national scale.

The latest pilots have established several best practices that other states should implement. Oregon’s OReGo program is one of the most advanced RUC pilots, charging 1.7 cents per mile. The pilot started with extensive research, testing, and public outreach, and has now been scaled to allow for 5,000 program participants. Each participant can choose between using a GPS or non-GPS mileage reporting device. The program has also contracted with two separate vendor companies to operate the service, ensuring a competitive enterprise and limiting the state’s risk exposure. Further, the program operates under strict privacy policies and procedures to protect user data, including requiring the vendors to:

  • Complete and maintain account manager certifications, subject to regular verification;
  • Transmit only general zone information and total mileage to the Oregon Department of Transportation; and
  • Destroy any collected data within 30 days.17

This model—relying on extensive public outreach, the use of separate and non-governmental vendors, and a variety of data reporting options for drivers—should be seen as the gold standard going forward.

While fuel user fees cannot sustainably fund the HTF in the long term, the simplicity with which it is collected does have several benefits that should be considered in the transition to a VMT fee. For one, fuel user fees are near universal and collected at, or near, their point of use. Personal and industry road usage does not stop at state boundaries and, as such, creating a compatible interstate system will be key to appropriately allocating VMT revenues to the jurisdictions that drivers are using. Regional coalitions such as the Western Road Usage Charge Consortium and the I-95 Coalition have been vital resources for the dissemination of best practices and the promotion of interstate collaboration. Further expanding and supporting these regional efforts will be critical for successful implementation of any nationally scaled VMT fee.

Fuel user fees also indirectly account for the weight of a vehicle through decreased fuel efficiency. A vehicle’s weight translates into the level of damage, or wear and tear, a given vehicle inflicts on roadways.18 In the strictest application of the user-pay, user-benefit model, users inflicting the most damage on roads should bear responsibility for a proportional share of maintenance and repair costs. To equitably account for the impacts of heavier and lighter vehicles, a standardized VMT fee would need to also take vehicle weight into account. Proposed “smart” RUC systems that enable GPS features are also capable of distinguishing between road types, which would provide for a more accurate picture of maintenance costs based on road surface materials.

The upcoming surface transportation reauthorization should dramatically expand the STSFA grant program and mandate that each state DOT develops and begins testing a plan to implement a VMT user fee, deploying the best practices derived from existing pilots.

Restore congressionally directed spending, with safeguards.

While most Americans recognize the poor state of our infrastructure, and that it is holding back our economy, public support for raising taxes to repair, replace, and upgrade that infrastructure can be tepid. Yet at the local level, ballot initiatives for transportation pass at twice the rate of other ballot measures.19 In such efforts, one of the keys to success is clear communication with the public about the benefits they can expect from paying more and, conversely, the consequences of inadequate funding.

To that end, restoring congressionally directed spending in a more effective, transparent, and accountable system would help to increase the ability of members in Congress to take on tough issues that are critical to the national interest, like increasing the gas tax. By affording members of Congress the opportunity to secure funding for the highest priority transportation needs in their districts, congressionally directed spending would make lawmakers more invested in the process, engage them in the hard work of governing a polarized and divided country, and give them a tangible benefit to show to constituents who are asked to pay more.

To create an effective and transparent system, one in which members of Congress can openly pursue projects to address their constituents’ needs, congressionally directed spending should be restored along with safeguards—increased transparency, a more robust vetting process, and reasonable limits on direct spending.


Concluding Thoughts

We recognize the many challenges inherent in fixing the Highway Trust Fund. However, it is clear to us the contours of a bipartisan agreement exist:

  1. Increase fuel user fees for the last time and index them to inflation.
  2. Strengthen the user-pay, user-benefit model.
  3. Prepare for a transition to a user fee based on vehicle miles traveled.
  4. Restore congressionally directed spending, with safeguards.

Our roadmap is the most fiscally responsible and politically viable solution on the table. It is time to increase the gas tax one last time and take necessary steps to more sustainably fund our critical transportation systems for decades to come.

End Notes

1 Peter G. Peterson Foundation, “The Highway Trust Fund Explained,” June 2018. Available at:
2 Congressional Budget Office, “Highway Trust Fund Accounts,” May 2019. Available at:
3 Jeff Davis, Eno Center for Transportation, “CBO Updates 10-Year Cost of HTF Solvency to $176 Billion,” May 2019. Available at:
4 Ed Regan, CDM Smith, “The Motor Fuel Tax: A Critical System at Risk.” Available at:
5 Luas Davis and James Sallee, “Should Electric Vehicle Drivers Pay a Mileage Tax?” July 2019. Available at:
6 Alliance of Automobile Manufacturers, “Advanced Technology Vehicle Sales Dashboard,” 2019. Available at: David Gohlke and Yan Zhou, Argonne National Laboratory, “Assessment of Light-Duty Plug-In Electric Vehicles in the United States, 2010–2018,” March 2019. Available at:
7 American Automobile Association, “AAA: 1-in-5 U.S. Drivers Want an Electric Vehicle,” May 2018. Available at:
8 National Conference of State Legislatures, “Recent Legislative Actions Likely to Change Gas Taxes,” June 2019. Available at:
9 U.S. Bureau of Labor Statistics, “Consumer Expenditures—2018,” September 2019. Available at:
10 Based on authors’ calculations using data from the U.S. Bureau of Labor Statistics. Available at:
11 Kimberly Amadeo, The Balance, “Regressive Tax with Examples,” April 2019. Available at:
12 National Conference of State Legislatures, “Recent Legislative Actions Likely to Change Gas Taxes,” June 2019. Available at:
13 American Association of State Highway and Transportation Officials, “Federal Highway Funding Formulas,” January 2019. Available at:
14 Jianwei Xing, Benjamin Leard, and Shanjun Li, “What Does an Electric Vehicle Replace?” April 2019. Available at:
15 National Surface Transportation Infrastructure Financing Commission, “Paying Our Way: A New Framework for Transportation Finance,” February 2009. Available at:
16 National Conference of State Legislatures, “Road Use Charges (RUC),” April 2018. Available at:
17 Oregon Department of Transportation, “Oregon’s Road Usage Charge,” April 2017. Available at:
18 Robert Atkinson, “A Policymaker’s Guide to Road User Charges,” April 2019. Available at:
19 Transportation for America, “Saving the Nation’s Transportation Fund,” 2013. Available at:

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