America’s electric vehicle transition is accelerating — good news for the environment and our long-term energy sustainability. Buried inside this success story is a growing fiscal problem that policymakers have quietly papered over for more than a decade. The more Americans switch to electric vehicles, the more precarious the nation’s road funding system becomes. Unless lawmakers modernize how roads are funded, the electric vehicle boom could worsen an already fragile system.

There is a clear path forward.

The problem is straightforward. Federal highways are primarily funded through fuel taxes deposited into the Highway Trust Fund. Electric vehicles don’t use gasoline or diesel, allowing their owners to evade the primary user-fee system that maintains those roads.

The warnings have been clear for years. Without a fresh infusion of cash, the Highway Trust Fund will be unable to meet its obligations within the decade. And there have already been many bailouts. 

Since 2008, Congress has transferred more than $275 billion into the trust fund to prevent insolvency, according to the non-partisan Congressional Research Service. That is money borrowed or diverted from other important areas to prop up what was designed to be a self-sustaining road maintenance system.

Meanwhile, the nation’s roads are deteriorating. The American Society of Civil Engineers most recently gave U.S. roads a D grade and identified a massive infrastructure funding gap. 

Drivers feel those costs directly. Vehicle ownership expenses remain high, and poor road conditions mean more trips to the mechanic. 

Now, layer in the electric vehicle transition. The International Energy Agency reports that U.S. electric vehicle sales have reached record levels in recent years, reflecting rapid market growth. At the same time, data from the Federal Highway Administration shows that total vehicle miles traveled remain historically elevated. In simple terms: Americans are driving a lot — and a growing share of those miles are powered by tax-free electricity rather than gasoline.] That means more wear and tear on our roads without corresponding gas tax revenues.

Some states have responded by imposing flat annual registration fees on electric vehicles. Flat fees are blunt instruments. A driver who travels 5,000 miles a year pays the same as one who drives 25,000. That undermines the user-pays principle that originally justified the gas tax.

This is why many experts have proposed vehicle miles traveled, or VMT, fees. Under these programs, drivers pay based on the number of miles they drive, regardless of fuel type. Analysts at the Brookings Institution have shown that mileage-based fees better align road use with road funding.

Everyone wants fairness when it comes to who pays for roads. To be sure, VMT systems raise some concerns. Some versions rely on GPS-enabled devices or smartphone apps to track mileage. Civil liberties advocates have objected to perceived privacy risks and data security vulnerabilities and public skepticism toward digital tracking is not trivial in an era of frequent data breaches. These challenges can be overcome.

Oregon has become a national test case. Its OReGO program allows drivers to pay a VMT charge instead of the state gas tax, demonstrating how a mileage-based system can be implemented. The program shows that such systems are practical and can offer flexibility to address privacy concerns. 

For example, while GPS trackers can be used to measure mileage, drivers also have the option to manually submit photos of their odometer readings, eliminating the need for tracking altogether.

The current model of generating revenue for road maintenance is clearly unsustainable. Congress cannot indefinitely transfer general revenue into the Highway Trust Fund while encouraging a shift away from gasoline consumption.

Roads are used by everyone — including electric vehicle drivers — and they are wearing out. The funding system that maintains them must evolve accordingly.

If America wants an electric future, it also needs a funding system built for one.

Louis Sigaud is a freelance writer from Maine. He wrote this for InsideSources.com.