When assembling data for the donor state article elsewhere in this issue, something leaped out at me – the fact that Texas paid more gasoline tax into the federal Highway Trust Fund in 2022 than did California ($2.913 billion to $2.735 billion), despite Texas still having 9 million fewer residents (39.0 million vs 30.0 million).

Texas has had a lead in diesel and trucking taxes for a while, based on the freight sector and NAFTA traffic, but taking the lead in gas tax payments, directed by individual consumers, is recent, and it led me to look back a bit further to try and spot a trend. I looked every five years back to 2007 (before that, FHWA used a different method for reporting taxes because of an ethanol issue).

Over the last 15 years, California’s gasoline tax payments have dropped to 97.2 percent of their 2007 level, while Texas’s have gone up to 139.9 percent of their 2007 level. (The U.S. total is 110.6 percent of the 2007 level.) And since the rate of tax has not changed since 2007, that means that gallons of gasoline used on highways has decreased or increased by the same amount.

Some of this difference is doubtless due to relative population increases. Using the Census Bureau’s official intercensal estimates, the Golden State’s population has increased by 7.7 percent since 2007, while the Lone Star State’s residents have increased by 26 percent. (The U.S. average was a 10.6 percent increase.)

Looked at that way, you can also derive the per capita cost of the federal gasoline tax to residents of each state. (This excludes the diesel and trucking taxes, which, unless you drive a personal diesel vehicle, get passed on to you indirectly.)

Is the difference just about the population? Here are the official FHWA estimates for total vehicle-miles-traveled (VMT) in both states (this includes truck traffic as well, it’s not easy to sort them out):

And then it’s easy to derive VMT per capita, which shows it’s clearly not just about raw population growth:

The average Californian drove 1,627 fewer miles than the average Texan in 2022. The TX to CA per capita VMT ratio was 1.1 to 1 as recently as five years ago but has now grown to 1.2 to 1 (probably COVID-related).

If population and VMT aren’t the whole story, the remaining bit has to be the fuel efficiency of the vehicles, where California has taken the national lead in restricting the gas-guzzling vehicle options available for sale in the state (and raising gasoline taxes so high that demand for more efficient cars is higher than in the rest of the country). Texas, meanwhile, has a cultural encouragement of large vehicles and a lot of road built for high speeds.

It’s fairly easy to convert per capita fuel tax payments to per capita gasoline consumption:

Since 2007, California’s per capita gasoline consumption has dropped by almost 10 percent, where in Texas it has increased by 11 percent. And that means…

Using the EPA standard of each gallon of gasoline used in an engine producing 8.887 kilograms of CO2, it seems that the average Texan produces 1.3 metric tons more of CO2 from driving cars and trucks than does the average Californian (4.7 tons vs 3.4 tons).