States are looking for ways to keep the funds coming in order to maintain the nation's roads.
Gas taxes have been used for more than a century for the purpose.
The problem that has developed is those taxes are generating less each year due to inflation, fuel efficiency and the rise of electric cars.
States are experimenting with various ideas that could eventually replace those taxes.
One proposal that seems to be gaining in popularity would be to charge drivers by the mile instead of the gallon.
Other ideas that have been presented include taxing electricity from public vehicle charging stations.
Another is to tack charges onto door-to-door package deliveries.
States are now weighing whether to start making the programs mandatory.
In 2015, Oregon began a pilot program charging motorists by the distance their vehicle travels rather than the gas it guzzles.
To participate, drivers plug a device into their vehicle and create an account to capture mileage data.
The federal government is about to pilot its own program, funded by $125 million from President Biden's infrastructure measure that he signed in November 2021.
So far, only three states, Oregon, Utah and Virginia are generating revenue from road usage charges.
Hawaii will join them next.
Last year, Colorado began adding a 27-cent tax to home deliveries from Amazon and other online retailers to help fund transportation projects.
Other states have been testing electronic toll systems.
Electric car sales in the U.S. rose from just 0.1% of total car sales in 2011 to 4.6% in 2021, according to the U.S. Bureau of Labor Statistics.
S&P Global Mobility forecasts they will make up 40% of the sales by 2030.
The National Transportation Finance Center at San Jose State University’s Mineta Transportation Institute has conducted national surveys every year since 2010.
According to the institute's director, Asha Weinstein Agrawal, there is growing support for mileage-based fees, special rates for low-income drivers and rates tied to how much pollution a vehicle generates.
The Associated Press contributed to this report.