In early 2017 I wrote a primer on the future of the fuel tax.  The topic got away from me and ended up turning into a fairly comprehensive look at how roads have been historically paid for and what options are available in the future.  The paper became a presentation, and the pair of products won the 2017 student paper competition for the ITE Utah Section.

ABSTRACT: This paper considers the long-term stability of highway finance which funds the maintenance and expansion of America’s highway system. It explores the current revenue stream, which mostly consists of fuel excise taxes. This revenue source falls short of meeting the country’s growing demand for highway infrastructure spending. The situation is further compounded with new vehicles, particularly electric-powered ones, which do not pay fuel taxes while still consuming miles on the road. Traditional gasoline-powered cars are seeing improved fuel economy, consumer fewer gallons, and pay less tax. Inflation has also robbed the fuel excise tax of its construction buying power. As an alternative to traditional funding, toll roads seem a promising solution. However, several new facilities do not meet projected traffic volume needed to justify the expense of their construction. Another alternative revenue source is changing a flat by-the-mile tax, which Oregon is currently piloting. This shows promise of being a long-term stable funding source, but has equity problems. Some consider changing a flat-rate mileage tax to have an unintended consequence of subsidizing vehicles with poor fuel economy. Others fear governmental intrusion as states collect driving data for taxation purposes. Policymakers would need to address those issues before such a tax could be politically palatable.



Highway funding in the United States sources the bulk of its revenue from gasoline and diesel excise taxes which are charged to wholesalers and passed onto customers at the pump. Each state’s fuel tax generates revenue for state departments of transportation to maintain and expand state highways. The federal tax is distributed as federal-aid money for interstate and U.S. trunk network highways, as well as helping to pay for projects funded in 5-year transportation bills. Through inflation and improving fuel economy this mechanism has lost much of its buying power since the tax was last raised. There is a need to find a reliable source of revenue for coming decades to maintain and expand our aging highway system.

The purpose of this paper is to explore the existing sources of revenue to see what strengths, weaknesses, and opportunities exist for stable long-term funding for highway maintenance, congestion relief, and expansion. Options being considered include raising the existing fuel excise tax, relying on building more tolled facilities, implementing “green” environmental taxes, and imposing a vehicle-miles travelled (VMT) tax.

This paper will explore and discuss the current shortfalls in highway funding. This includes a current $100-billion-dollar deficit in the most recent Congressional surface transportation bill, income erosion from inflation and increased fuel economy, and liabilities with traditional tolling. Then this paper will explore the proposed new sources of revenue that could supplement or replace existing funding sources, and address potential problems that could arise. This includes past failures of public-private toll roads, the political challenge of raising fuel excise taxes, equity problems that exist with “green” taxes, and an unfair distribution of the burden on fuel-efficient vehicles under a VMT tax.


Every five to seven years Congress passes a funding authorization bill that determines how highway user fees are spent to maintain and expand surface transportation. On December 3, 2015, President Barack Obama signed the Fixing America’s Surface Transportation Act. It spends $305 billion dollars over five years. However, federal fuel excise taxes, which pay for the bulk of transportation funding, will likely collect only $205 billion dollars over the next five years (1). This creates a $100-billion-dollar shortfall.

Much of America’s transportation infrastructure was built as part of the post-war highway construction boom, which included the Eisenhower Interstate System. Much of this infrastructure has not been replaced and is now reaching the end of its usable and functional lifespan. The American Society of Civil Engineers rates America’s roads and transit with a “D” grade (2). Some policy think-tanks estimate the county may need to spend $1 trillion dollars in the coming decades, on top of what is already spent (3). The existing motor fuel excise tax faces growing challenges which do not, at present, meet the demands of current and future five-year spending bills. Traditional tolling is an alternative some states consider, but it can face financial problems.

Motor Fuel Excise Tax

A tax on transportation petroleum products first appeared when President Herbert Hoover signed a temporary one-cent per gallon tax in the Revenue Act of 1932. The nation had a fiscal crisis and government leaders saw capitalizing on the emerging auto industry as a way to balance the budget (4). None of this money was earmarked directly for transportation purposes, and went solely to the general fund to be spent however Congress wanted. The tax remained ever since. In the 1950s, the Highway Revenue Act of 1956 was enacted to create the Highway Trust Fund and earmarked the fuel tax only for roadway spending. Fuel tax revenue replenishes the trust fund. Today the majority funding for highway construction and maintenance comes from federal and state motor fuel taxes. The rate was not indexed to inflation and required congressional legislation to raise it. Hikes occurred approximately every 5-10 years until the early 1960s and was not raised again until the 1980s (4).

The federal gas tax is 18.4 cents per gallon of gasoline and gasohol, 24.4 cents for diesel fuel, and 48.5 cents per 1000 cubic feet of compressed natural gas. These rates have not been updated since 1997 even though construction costs have continued to increase since then (5). Similar excise taxes exist for liquefied petroleum, natural gas, and methanol blends. These were raised in 2006, but are also not indexed to inflation. Inflation erodes the tax’s ability to serve the transportation needs it is intended to fund. The fuel tax reached its highest level in the early 1960s (adjusted for inflation), during the peak of the freeway construction boom (4).

All 50 states collect a state excise tax on top of the federal one. On average, states change 20.72 cents per gallon for gasoline and 20.44 cents for diesel fuel, per gallon. Coastal states, which have higher cost of living, have higher tax rates. For instance, Washington, Hawaii, New York, and Pennsylvania have combined federal and local excise taxes that exceed 60 cents per gallon. Southern states are generally lowest at around 40 cents. The rest fall somewhere between 40 and 60 cents per gallon (6).

The federal government also imposes non-fuel taxes whose proceeds go directly to the highway account. These include a tax on all semi-truck-rated tires (passenger car tires have no federal tax), a 12 percent sales tax on all new semi-trucks and trailers, and an annual Heavy Vehicle Use tax up to $550 dollars per year per vehicle (5). Income from these taxes is not inconsequential, as the trucking industry is a significant user and contributor to the highway system. During Hurricane Katrina a temporary jump in fuel prices lead to several states, including Georgia, Massachusetts, and Connecticut to temporarily suspend collection of state fuel taxes on gasoline to provide relief at the pump for drivers. Lawmakers feared high gasoline prices would throw the state economy into a recession and lead to higher unemployment. But a University of Nebraska study found that had the tax holiday been applied to diesel fuel instead, there may have been a higher economic benefit (7). It demonstrated the enormous economic impact semi-trucks have on the economy.

The combined federal and state taxes generate roughly $41 billion dollars per year (8). About $18.4 billion remains with the federal government with the remainder being state taxes sent back to where they were collected (6). As significant as that is, the income stream falls short of the $61 billion dollars authorized in the most recent surface transportation bill (9).

Increasing spending and inflationary erosion are not the only two budgetary bullets highway projects must dodge. Stringent new regulation, particularly in recent years, as well as consumer demand have driven significant improvement in fuel efficiency across America’s vehicle fleet. Figures from the U.S. Environmental Protection Agency (EPA) show the average fuel economy for gasoline and diesel vehicles in 1975 at 13.1 miles per gallon. This has now nearly doubled to 24.0 miles per gallon in 2013 (10). Transportation agencies now get 50 cents (adjusted for inflation) per vehicle mile traveled that they would have received a dollar for just a generation ago.

This savings, along with other socioeconomic shifts, have led to Americans driving significantly more than they did a half century ago. A motorist today drives three times more miles than he or she would have in 1960. The Federal Highway Administration believes this growth may now be leveling off, but the high travel amount remains (4). Synthesize these two pictures together, and we see agencies attempting to accommodate $6-dollars-worth of travel on a budget of just $1.50.

Five-Year Transportation Bills

The Fixing America’s Surface Transportation Act is one of a long line of five-year surface transportation bills which Congress has passed to dole out money collected from user fees, primarily from the gas tax. Federal-aid highway bills regularly authorized spending from the end of World War II through 1987. Formal surface transportation bills were passed in 1991, 1995, 1998, 2005, 2012, and 2015. Since the Intermodal Surface Transportation Act of 1991, these bills do not exclusively fund roadway projects. Highway agencies share revenue, or at least a small fraction of it, with transit agencies (11). Transit does offer an opportunity to reduce VMT and stress on the roadway network in the future, but it adds stress to highway expansion and maintenance budgets.

Revenue shortfalls do not appear to deter the country’s appetite for highway spending. Despite being $100 billion dollars short for the 2012 spending bill, Congress managed to gather the money it needed by dipping into unrelated sources. The most creative was raiding money collected from cigarette taxes to close the funding gap. Some retailers offer roll-your-own-tobacco machines, which is subject to a specific federal tax. This revenue was siphoned off to close the shortfall in the Progress in the 21st Century Act of 2012, even though there is no direct connection between hand-rolled tobacco products and highway infrastructure (12). This is an unsustainable collision of our current funding limitations and our hunger for transportation. As of 2002, fuel taxes only covered 39 percent of highway expenditures. When this is combined with other user fees, such as vehicle registration fees and toll revenue, it totals just shy of 60 percent. This leaves two-fifths of all highway spending reliant on non-user fees, such as bonds, sales taxes, property taxes, or simply raiding the general fund account (13).

Traditional Tolling

Tolling generally appears on routes in east-coast states where population centers, and a need to connect them with roads, existed before the Interstate Act. Texas stands out as an anomaly among western states. The state has built 25 tolled facilities to stretch transportation dollars for new high-capacity, high-speed routes in rapidly growing metropolitan areas (14). But a shift in public opinion may slow the Lone Star State’s lust for tolling. The Texas Legislature has listened to cash-strapped motorists and advocacy groups who say tolling is double taxation. They argue fuel excise taxes are constant for all drivers regardless if a commuter must use a toll road or a free road. Lawmakers have shown a willingness to boost state transportation spending by billions, but with a caveat that not a single penny be spent on tolled projects. This leaves new toll roads in Dallas, Austin, and San Antonio in limbo; a may signal of a new Texas political climate that will shifted away from tolling for the foreseeable future (15).

Even in places where tolling is politically palatable, it is not automatically a trouble-free revenue generator. In the 1990s, officials in Orange County, California sold $2.2 billion worth of bonds to pay for the construction of a network of toll roads through the San Joaquin Hills east of Irvine, California. These roads were intended to be a self-funding reliever to the busy CA-55 and CA-91 freeways. However, traffic congestion persists on those free routes and traffic volume on the tollway network is far below what planners anticipated. In 2011, county supervisors were forced to re-finance the bonds, which pushed repayment from 2036 to 2046 – not unlike a cash-strapped family struggling to make their mortgage payment refinances for extra years in exchange for a lower minimum monthly payment. The situation did not improve and within 3 years, county supervisors voted a second time to re-finance the road, pushing payoff to 2050 or beyond (16). Elected officials in other regions may question the wisdom of building a toll road as they see drivers in one of the country’s wealthiest (and most congested) counties avoiding tolled routes.


To meet America’s growing appetite for highway maintenance and expansion, a number of new potential funding mechanisms are in play. These include taxes include new fees on environmental impact, which can have a negative impact on poor and working-class motorists, with income not likely to be spent on highways. Some states are increasing existing excise taxes and indexing them to inflation. New methods for collecting road tolls and the emergence of public-private partnerships offer new opportunities for building tolled routes. Advances in electronic data collection allow one state to pilot a program where they charge drivers by the mile, but it may place an unfair burden on fuel-efficient vehicles.

Climate Change and Emission Taxes

Ten years ago, Governor Arnold Schwarzenegger of California signed into law the Global Warming Final Solutions Act. This law imposed a new green tax on 450 producers of greenhouse gas emissions, which includes transportation fuels. The intention was to diversify California’s use of fuels — promote burning cleaner fuels, such as methanol, natural gas, and hydrogen. Eventually the state’s residents would reduce or eliminate the use of fossil fuels entirely (17). Other major contributors to the bucket of climate change money include large industrial facilities in California and electrical generation stations that use fossil fuels. The law mandates ever dollar generated be used to reduce greenhouse gas. The first distribution of funds granted 14 transit agencies nearly $400 million dollars for new transit projects (18). Although this does not fund highways directly (state law prohibits money from being used on highway construction), transit provides an alternative where economic activity can continue and indirectly provide highway congestion relief.

Prior to this law in 2004, the California Air Resources Board (CARB) considered creating an emission per mile tax based on how dirty a vehicle’s emissions are and how far a motorist drives per year. A study published in the Journal of Transport Economics and Policy found such a tax would have a disproportionate burden on the poor, despite lower-income individuals driving fewer miles. When adjusted for travel, age and condition of vehicle, and income, the study found the burden on wealthier populations scored 0.14, while the burden for the lowest income group scored 0.65. As a percentage of total household income, lower income families would feel the burden five-times more heavily. The emission tax was never implemented (19).

Raising State Motor Fuel Taxes and Index to Inflation

States with rapidly growing metropolitan areas do not appear to be waiting for Congress to find a national funding solution. After a long period of no state approving a fuel tax hike, a flurry of states did so in the past few years: Six in 2013, three more in 2014, and eight in 2015 (20). One of the most noteworthy was New Jersey, whose legislature raised their tax an astonishing 23 cents in 2016, more than doubling the existing 14.5 cents to a new total of 37.5 cents per gallon. This is that state’s first fuel tax hike since 1988 (21). States who indexed the tax to automatically increase with inflation or the consumer price index include Georgia, Michigan, North Carolina, Utah, New Hampshire, Rhode Island, Massachusetts, Maryland, Pennsylvania, and Nevada (20).

A metropolitan planning agency for Las Vegas says fuel indexing will pay for over 200 new transportation projects in coming years valued at over $700 million dollars, which will cost a typical driver 10 cents extra per day. Most notably, an entire new Interstate that bypasses Boulder City, Nevada and connects Las Vegas to the Arizona border is paid for primarily through index funds (23).

Electronic Toll Collection

Traditional tolling methods pose three problems: First, toll collection has high administrative costs as agencies hire a small army of toll booth collection attendants. Second, the toll booths themselves pose a safety and performance problem, as they are placed in-lanes on a high-speed facility. Third, booths have a slow service rate as motorists must have cash in hand and cause delays while they find or make change.

Many of these problems are disappearing with the roll out of electronic toll collection (ETC) which first appeared in late-1980s. Agencies began organically developing their own toll collection systems and the Federal Highway Administration saw promise in the technology. A recent five-year transportation funding bill mandated that all non-electronic forms of tolling should be eliminated by the end of 2016 (24). ETC transponders are typically windshield-mounted transponder tags which allow motorists to pay a toll without stopping. This allows demolition of toll plazas and helps toll roads perform more like a toll-free facility. ETC allows agencies to vary toll prices based on congestion, which has been useful on high-occupancy-toll (HOT) lanes.

The problem appears when a person leaves their metropolitan area and attempts to use their ETC transponder in another region. The same bill mandated toll collection systems become interoperable, but provides no road map to accomplish the goal. Departments of Transportation and toll agencies in 35 states have invested hundreds of millions of dollars in their toll collection equipment. Interoperability would likely require scrapping much of that investment and starting over. Some states in the northeast have formed an interoperability agreement, and a few states in the south have done similarly with their own separate interoperable system (25). Until a transponder works nationally, it may be easy for a driver to not consider the monthly maintenance cost worth paying. Without an ETC transponder, drivers will continue to avoid toll roads which contributes to low use.

Public-Private Partnerships

Enthusiasm for new toll collection methods infected the country’s appetite for constructing new toll roads in the early 00s. The administration of President George W. Bush actively promoted forming public-private partnerships. This new form of highway project delivery promised world-class infrastructure, relatively little upfront cost, and a sustainable revenue stream. Mary Peters, who served as President Bush’s Secretary of Transportation, championed a “market-based approach to transportation” which included privatizing highways and making tolling more permissive for states (26).

Texas attempted one of the most ambitious public-private highway projects in U.S. history. In 2006, the state signed an agreement with a local contractor and a European infrastructure investment firm to build, operate, and maintain a new 41-mile extension to the Texas 130 toll road outside Austin. In return, Texas lawmakers would allow the consortium to collect and keep toll revenue for 50 years. This would pay back the project’s $1.3-billion-dollar up-front cost, fund maintenance, and hopefully make a reasonable profit for all parties involved. To incentivize use of the new toll road, the Texas Department of Transportation approved an 85-mile-per-hour speed limit, the first and only of its kind in the entire country (27).

But like the Orange County toll roads a decade before, problems for Texas 130 appeared from day one. Traffic was light as drivers continued using parallel (and free) I-35 route. This left toll revenue far short of what investors expected. A major bond credit-rating service downgraded the consortium’s debt, including a $430 million bond owed to the U.S. Department of Transportation. By 2014, the road’s operators admitted traffic volume was only 30 percent of initial projections. Lenders allowed the consortium to defer debt payments until early 2016. When the time came, they could not pay. The toll road filed for Chapter 11 bankruptcy and the two-company consortium began authoring a plan to walk away from Texas 130 entirely. This leaves lenders to figure out how to proceed (27).

San Diego already experienced a failed toll road. In the late-1980s, California approved public-private partnership legislation for a new $610-million-dollar toll concession project. Unlike the Texas 130 project where the road was built entirely by the toll franchisee, Caltrans owns the South Bay Expressway but leased the toll concession back to the investor (28). When the road opened in 2007, it was considered the “next big thing” in regional commuting, and touted as a model for public-private partnerships. But only 26,000 vehicles per day used the road, far below the 60,000 anticipated to use it. The economic crash of 2008 added salt to the wound as travel dipped to just 22,500 vehicles per day. The concession company found themselves $16-million-dollars short on their payment to lenders each year. By 2010, they filed for bankruptcy (29).

The San Diego Association of Governments saw the value of the South Bay Expressway. The agency issued bonds to purchase the road which it converted into a traditional toll road (30). Their goal is to retire the bonds as quickly as possible by making it part of their regional transportation plan. This will allow the South Bay Expressway to one day become a freeway, though this may still take up to 30 years to achieve (31).

Vehicle-Miles-Traveled Tax

Among concerns about the motor fuel excise tax is the increasing percentage of vehicles not powered by motor fuels at all. The number of electric vehicles (EVs) sold during 2015 is more than double those sold just three years beforehand. Last year over 100,000 new EVs were registered on America’s roadways. This year is projected to see a one-year increase of 33 percent (32). While 500,000 vehicles are still just a tiny fraction of the 290 million registered vehicles in the United States, it demonstrates a growing fraction of cars that get a “free ride” on public roads – while consuming no motor fuel and paying no motor fuel excise tax.

Oregon is among a few states considering charging motorists per VMT in lieu of the tradition gas tax. In 2001, the state’s legislature formed a task force to explore new ways of funding highway maintenance and improvements. A decade later the task force introduced a pay-by-the-mile meter, which about 80 volunteers installed in their vehicles. The meter collects mileage data from the car’s computer and multiplies it by 1.5 cents to determine an annual tax bill. Once paid, volunteers apply for a refund for all the state gas tax they paid during the year. In 2013, new legislation expanded the pilot program to 5,000 volunteers and officially named it “OReGO.” If the program is successful, it will replace state fuel excise tax entirely (33).

A benefit of a VMT tax include being able to bill all motorists, regardless of vehicle type, at the point of consumption. The charge could be indexed to inflation from day one. Ride-sharing and taxi services could tie into the system electronically so taxes could be billed directly to the passenger.

OReGO charges a flat cents-per-mile fee, but other states may propose systems that are more invasive. These could mine data from the car’s computer to determine what routes a motorist drives and during what time of day. Tax rates could be higher during congested periods. Money collected from travel on a specific roadway could be automatically be budgeted to making improvements on that very roadway. This presents very real privacy concerns for some drivers. A nationally-syndicated newspaper columnist questioned the OReGO program and asked “Do we really want the government collecting data about driving habits?” While OReGO assures participates that their program does not collect global-positioning-system (GPS) data, distrust for elected officials may cause some to fear the program anyway (34).

Interoperability again emerges as a concern. Mileage collection will not work across states lines. If all states switch to VMT mileage collection, commuters who live in one state but work in another may not be charged road tax in the state they do not live in. The tax also seems easy to defeat. Excise tax is collected from wholesalers, who are easy to audit and keep in compliance. A VMT tax is collected from millions of users. Circumvention may be as easy as driving with the collection device unplugged.

An immediate concern with OReGO is that it treats all miles equally, regardless of vehicle. An online calculator allows potential OReGO users to approximate their tax bill. For instance, a motorist who drives 1000 miles per month at 20 miles per gallon would pay $15 dollars per month under the fuel excise tax and $15 dollars per month under OReGO. But if fuel economy improved to 30 miles per gallon, the fuel excise tax drops to $10 dollars, while OReGO remains at $15. Likewise, a large sport-utility vehicle at 10 miles per gallon would see a $30 dollar per month tax under the state fuel tax, but still only $15 dollars with OReGO (35). Oregon’s VMT tax loses the present reward structure for fuel efficient vehicles and a perception that prudent individuals in economy cars are forced into subsidizing less-efficient vehicles. A local tabloid blasted OReGO as rewarding “Hummers over hybrids” (36). Academics seem to agree. In the study on the equity implications of a CARB vehicle emissions tax, the study’s author dismissed a uniform VMT tax because the it penalizes clean vehicles equally to driving a dirty vehicle (19).


There is no such thing as a free highway. Whichever funding mechanism is selected, taxpayers will still open their wallet to pay for highway maintenance and expansion. Policymakers should find an equitable solution where each user paying a fair share. No particular vehicle should get a free ride, as presently exists for hydrogen and electric vehicles under federal and state motor fuel excise taxes. The new policy should not put a disproportional burden on low-income and working-class households, nor should it reward gas guzzlers. The funding source should be stable and robust to endure changes in price over time.

With these constraints it becomes apparent why a VMT-based fee, if equity concerns are address, appears so promising. But policymakers will need to determine on a philosophical level why a vehicle is paying tax. If it is because a motorist’s vehicle is a single traffic count in the middle of a traffic congestion puzzle, the present Oregon-based solution of a flat fee per vehicle, regardless of size, could arguably be equitable (e.g., a Toyota Prius and a Chevy Suburban occupy the same amount of space in a freeway jam). But if vehicle tax is collected for the maintenance of the pavement itself, one reasonably argues why a heavier vehicle warrants paying a heavier tax. Until that question is answered, it’s difficult to know how to proceed.

Politicians appear to be too quick to throw a funeral for the fuel excise tax. While it is true that the present tax structure does not produce enough revenue, it still generates a massive amount. Raising the fuel tax to cancel inflation erosion and automatically indexing it to inflation will fund a significant part of our highway needs for decades to come.

Tolled roadways promise fantastic benefits with almost no upfront cost. But several examples demonstrate instability with previously-built facilities, especially in western states. This leaves affected communities with the worst of both worlds: all of the cost, but only a portion of the benefit (since most motorists avoid using the road and continue to congest existing routes). Furthermore, tolled roads violate equity because some communities in a metropolitan area enjoy freeways while other communities must use tollways – but all taxpayers pay the same fuel taxes, sales taxes, etc. Perhaps an advanced GPS-based VMT tax would take this into account and offer a discount for motorists on tolled roads. If that’s the case, one may ask why even charge a toll at all?

Ultimately it would be a mistake made to view transportation funding as a one-size-fits-all approach. Perhaps a hybrid solution is best. Retain the old motor fuel excise tax for old-technology vehicles that consume motor fuels. These should be raised and indexed to make them useful and equitable to new taxes. Impose a new VMT-tax for vehicles on new-technology vehicles that do not use petroleum motor fuels (hydrogen and electric vehicles). This allows the fuel excise tax to gradually phase out as the marketplace slowly shifts away from gasoline vehicles to new technology.


This paper explored the needs for highway investment in the United States and the existing and potential revenue sources to fund maintenance and expansion, which includes federal and state excise taxes. This mechanism fails to meet America’s needs because inflation and improved fuel economy have robbed it of its buying power. Some states have raised their state gas tax and indexed it to inflation. Some states have built new tolled facilities, which promise very low up-front costs, but see lower-than-expected use. California implemented a “green” tax, but none of the money is spent directly on highways.

The purpose of this paper was to explore the shortfalls of these existing sources of revenue to see what strengths, weaknesses, and opportunities exist for stable long-term funding for highway maintenance, congestion relief, and expansion. Then the paper looked at new revenue sources proposed to see what opportunities exist for new stable revenue. Among the more promising ones is a vehicle-miles traveled tax, which Oregon is presently being testing. This treats all vehicles the same and ends the “free ride” electric vehicles owners currently enjoy. Equity is a serious question as large vehicles are charged the same price as economical vehicles. Recommendations were made to keep the existing system for combustion engine vehicles, with taxes indexed to inflation, and to impose a new VMT tax for non-petroleum-powered vehicles.


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